全文获取类型
收费全文 | 1257篇 |
免费 | 47篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 2篇 |
儿科学 | 24篇 |
妇产科学 | 10篇 |
基础医学 | 135篇 |
口腔科学 | 20篇 |
临床医学 | 104篇 |
内科学 | 300篇 |
皮肤病学 | 11篇 |
神经病学 | 45篇 |
特种医学 | 15篇 |
外科学 | 134篇 |
综合类 | 44篇 |
一般理论 | 1篇 |
预防医学 | 54篇 |
眼科学 | 33篇 |
药学 | 231篇 |
中国医学 | 18篇 |
肿瘤学 | 127篇 |
出版年
2023年 | 7篇 |
2022年 | 23篇 |
2021年 | 37篇 |
2020年 | 19篇 |
2019年 | 30篇 |
2018年 | 29篇 |
2017年 | 38篇 |
2016年 | 24篇 |
2015年 | 30篇 |
2014年 | 56篇 |
2013年 | 82篇 |
2012年 | 84篇 |
2011年 | 89篇 |
2010年 | 58篇 |
2009年 | 36篇 |
2008年 | 74篇 |
2007年 | 93篇 |
2006年 | 58篇 |
2005年 | 70篇 |
2004年 | 58篇 |
2003年 | 70篇 |
2002年 | 77篇 |
2001年 | 23篇 |
2000年 | 17篇 |
1999年 | 27篇 |
1998年 | 5篇 |
1997年 | 8篇 |
1996年 | 13篇 |
1995年 | 7篇 |
1994年 | 8篇 |
1993年 | 7篇 |
1992年 | 7篇 |
1991年 | 4篇 |
1990年 | 4篇 |
1989年 | 4篇 |
1988年 | 4篇 |
1987年 | 4篇 |
1986年 | 7篇 |
1985年 | 2篇 |
1983年 | 1篇 |
1982年 | 1篇 |
1980年 | 1篇 |
1979年 | 1篇 |
1975年 | 1篇 |
1974年 | 2篇 |
1973年 | 2篇 |
1969年 | 2篇 |
1968年 | 3篇 |
1962年 | 1篇 |
排序方式: 共有1308条查询结果,搜索用时 15 毫秒
101.
102.
Lin P Bueso-Ramos C Wilson CS Mansoor A Medeiros LJ 《The American journal of surgical pathology》2003,27(8):1104-1113
Waldenstrom macroglobulinemia (WM) is a clinicopathologic syndrome in which a B-cell neoplasm involving the bone marrow, usually lymphoplasmacytic lymphoma (LPL), is associated with immunoglobulin M paraprotein in the serum. Extramedullary involvement occurs in a subset of patients and is infrequently examined histologically. The files of M.D. Anderson Cancer Center were searched for patients with WM who underwent biopsy of one or more extramedullary sites during the course of disease. Each biopsy specimen was classified using the criteria of the World Health Organization classification. The study group consisted of 44 patients (26 men and 18 women), with a total of 51 specimens obtained from lymph nodes (n = 36), soft tissue (n = 4), spleen (n = 3), skin (n = 2), lung (n = 2), tonsils (n = 1), colon (n = 1), liver (n = 1), and gallbladder (n = 1). Lymphoplasmacytic lymphoma was the most common histologic type, in 40 (78%) samples. This category was morphologically heterogeneous and was further subclassified as lymphoplasmacytic (n = 21), lymphoplasmacytoid (n = 18), and polymorphous (n = 1). Four of these LPL cases morphologically resembled marginal zone B-cell lymphoma. Four additional samples were involved by diffuse large B-cell lymphoma, probably transformed from LPL. Three more samples were involved by LPL with unusual features: two were CD5-positive and one was a composite tumor with classical Hodgkin's disease. Other categories of lymphoma in this group of patients with WM included small lymphocytic lymphoma/chronic lymphocytic leukemia (n = 2), mantle cell lymphoma (n = 1), and follicular lymphoma (n = 1). Waldenstrom macroglobulinemia is most commonly associated with LPL but can rarely occur with other types of B-cell lymphoma. Lymphoplasmacytic lymphoma in patients with WM is morphologically heterogeneous and can be indistinguishable from marginal zone B-cell lymphoma. CD5+ B-cell lymphomas with features otherwise typical of LPL are rare, and we think these tumors are part of the spectrum of LPL. 相似文献
103.
Abstract
The possibility of using quantitative motion analysis for objective assessment of simple surgical dexterity is investigated
using the Imperial College Surgical Assessment Device (ICSAD) with qualitative analysis undertaken by inspection. Bench-top
knot tying and suturing skills were performed and examined for the ability to discriminate between surgeons of varying experience.
These exercises were found to discriminate significantly between junior and senior surgeons in terms of both time taken and
the number of movements required. The relation between time and motion was found to be variable depending on what skill was
being undertaken: simple suturing, suturing at depth, or knot tying (1.71 vs. 1.86 vs. 2.36; p = 0.002 for 1 vs. 2; p < 0.001 for others). When the number of movements in a minute (standardized movements per minute) were considered, both groups
were found to work at a similar rate, depending on the task, implying that the more experienced surgeon is more economical,
performing the same exercise with fewer moves rather than with higher speed. Motion analysis exhibits face and construct validity
and is a reliable assessment of simple surgical dexterity. Its use for objective assessment of dexterity and competence should
be encouraged. 相似文献
104.
Development of a HPLC method for the determination of cyclosporin-A in rat blood and plasma using naproxen as an internal standard 总被引:1,自引:0,他引:1
Zaghloul AA Hussain A Khan MA Ahsan F 《Journal of pharmaceutical and biomedical analysis》2003,31(6):1101-1107
An isocratic reversed phase high-performance liquid chromatographic (HPLC) method with ultraviolet detection at 205 nm has been developed for the determination of cyclosporin-A (CyA) in rat blood and plasma. Naproxen was successfully used as an internal standard. Blood or plasma samples were pretreated by liquid–liquid extraction with diethyl ether. The ether extract was evaporated and the residue was reconstituted in acetonitrile–0.04 M monobasic potassium phosphate buffer (pH 2.5) solvent mixture. After washing with n-hexane, 30 μl of the reconstituted solution was injected into HPLC system. Good chromatographic separation between CyA and internal standard peaks was achieved by using a stainless steel analytical column packed with 4 μm Nova-Pak Phenyl material. The system was operated at 75 °C using a mobile phase consisting of acetonitrile–0.04 M monobasic potassium phosphate (pH 2.5) (65:35 v/v) at a flow rate of 1 ml/min. The calibration curve for CyA in rat blood was linear over the tested concentration range of 0.0033–0.0166 M with a correlation coefficient of 0.989. For rat plasma, the range of the concentrations tested were between 0.002 and 0.0166 M and showed linearity with a correlation coefficient of 0.953. The intra- and inter-run precision and accuracy results were 1.24–21.87 and 3.1–12.23%, respectively. The low volume of blood or plasma needed (200 μl), simplicity of the extraction process, short run time (5 min) and low injection volume (30 μl) make this method suitable for quick and routine analysis. 相似文献
105.
PURPOSE: To prepare and evaluate a suppository dosage form of salbutamol sulfate. The prepared formulae with and without different concentrations of gels were tested for hardness, melting time, content uniformity, and drug release. The stability of some of the selected formulae was assessed. METHODS: Salbutamol sulfate was formulated as a rectal suppository with emulsifying fatty bases (suppocire and witepsol) and water-soluble bases (PEG) adopting the molding from a melt technique. Physical characteristics and dissolution profiles of the prepared formulations were determined as the responses. The effects of adding gels, methyl cellulose (MC), and Eudispert (Eud) and their concentrations (1, 3, and 6%) on these responses were also investigated. Formulations showing high rank order were scaled up for shelf-life stability study for one year. RESULTS: The results showed that all the investigated formulae have acceptable physical characteristics with respect to hardness, melting time (except F7), and uniformity of drug content. The amount of drug dissolved in 100 min of dissolution time was inversely affected by the melting point of the fatty base. The release from PEG bases was found to be molecular weight dependent. Addition of 1% MC or Eud gel increased the release from all the investigated formulae. Increasing gel concentration to 3% then to 6% showed different effects on the release. The degradation of salbutamol sulfate in the investigated formulae was found to be a first-order reaction. CONCLUSIONS: Rectal suppository of salbutamol sulfate could be prepared as an alternative to the oral dosage form to circumvent the first-pass metabolism. 相似文献
106.
PURPOSE: Infantile myofibromatosis is an uncommon tumor that occurs rarely in the periorbit and orbit. This article reports two cases of infantile myofibromatosis of the orbital adnexa and describes the associated clinical, histopathologic, and immunohistochemical findings. DESIGN: Two retrospective, interventional case reports with clinicopathologic correlation. INTERVENTION: Treatment consisted of excision of the tumors. MAIN OUTCOME MEASURES: Histologic and immunohistochemical evaluation and clinical evaluation for tumor recurrence. RESULTS: The first patient was a newborn male with a large tumor extending from his eyelid that was excised at day 2 of life. Histologic and immunohistochemistry analyses were used to make a diagnosis of infantile myofibromatosis. He remains disease free at age 7 years. The second case was a 6-year-old boy with a 1-month history of proptosis resulting from an orbital mass. Incisional biopsy revealed a tumor consistent with infantile myofibromatosis. He remains tumor free 12 months after complete gross surgical resection. CONCLUSIONS: Infantile myofibromatosis is an uncommon tumor that is rare in the orbit. Differential diagnosis can be difficult based solely on histologic analysis. Immunohistochemistry evaluation demonstrating cytoplasmic actin filaments within neoplastic spindle cells confirms the diagnosis. As soon as the diagnosis is made, chest and abdominal imaging is of value to define the prognosis and to direct further treatment. After the diagnosis of nonvisceral infantile myofibromatosis, complete gross resection, if possible, is the treatment of choice. 相似文献
107.
Several observations noted by early investigators supported the supposition that in most cases, congenital glaucoma is determined by genetic factors. The genetic heterogeneity of PCG was confirmed by genetic linkage studies conducted in the 1990s when the authors determined that CYP1B1 is the congenital glaucoma gene at the GLC3A locus. The coding sequence of CYP1B1 has been subjected to extensive screening in familial and sporadic cases of glaucoma from numerous countries and from a large number of ethnic groups. These studies have provided evidence for extensive allelic heterogeneity at the GLC3A locus. This article also discusses the molecular evidence for reduced penetrance in congenital glaucoma and the phenotypic heterogeneity of CYP1B1 mutations, mouse models of CYP1B1, and the biochemistry of CYP1B1. 相似文献
108.
Bates CJ Schneede J Mishra G Prentice A Mansoor MA 《European journal of clinical nutrition》2003,57(2):349-357
OBJECTIVE: Assessment of functional vitamin B(12) status in a subset of the respondents in the British National Diet and Nutrition Survey of people aged 65 y and over. SETTING: National Diet and Nutrition Survey: a British nationwide cross-sectional sample of people aged 65 y and over, living either in the community or in institutions such as nursing homes, during one calendar year spanning 1994-1995. METHODS: Methylmalonic acid (MMA) concentrations were measured in plasma samples from 313 subjects (ca 14% of those originally enrolled in the survey). The results were compared with those for serum vitamin B(12), vitamin B(12) intakes and other status and intake estimates and with socio-demographic indices. RESULTS: Of the NDNS participants overall, 20% had serum vitamin B(12) concentrations<150 pmol/l. In the subset studied here, 24% of free-living and 46% of institution-living participants had MMA>0.5 micromol/l. Geometric mean MMA increased with age, from 0.25 micro mol/l in people aged 65-74 y to 0.38 micro mol/l in people aged 85+y. There was little evidence for any gender difference in MMA. It was inversely correlated with serum vitamin B(12) and with red blood cell folate; it was positively correlated directly with total homocysteine, but not significantly with serum folate or with vitamin B(12) intake. Among respondents with high MMA, a subgroup had normal serum vitamin B(12) but higher-than-average plasma urea and creatinine. Socio-demographic co-variates of MMA included receipt of State income benefits, social class of head of household, and educational attainment. These indices were not correlated with serum vitamin B(12). CONCLUSIONS: The progressive increase in MMA with age is metabolic evidence for increasing risk of functional vitamin B(12) deficiency with increasing age in older people. There is evidence that renal function is linked to high MMA in some older people. Age and renal function are thus both important when establishing upper reference limits for MMA. The socio-demographic observations suggest a link between poverty and poor functional vitamin B(12) status in older British people. 相似文献
109.
Comparative analysis of molecular alterations in fibroadenomas associated or not with breast cancer 总被引:1,自引:0,他引:1
Franco N Arnould L Mege F Picard SF Arveux P Lizard-Nacol S 《Archives of surgery (Chicago, Ill. : 1960)》2003,138(3):291-295
HYPOTHESIS: The cause of breast cancer is linked to many macroscopic events, including benign breast disease. In this study we asked whether molecular changes could discriminate fibroadenoma, which is one of the most common benign breast disease lesions associated or not with breast cancer. DESIGN: Retrospective cohort study. SETTING: Anticancer medical center. SUBJECTS: Archival tissues in 32 cases of fibroadenoma, diagnosed in the same breast as a breast carcinoma, are compared with a control group of 26 cases of fibroadenomas unaffected by breast cancer. MAIN OUTCOME MEASURES: Histological features are characterized in all samples. The epithelial and stromal components are analyzed for a loss of heterozygosity and a microsatellite instability using a polymerase chain reaction-based method with 11 polymorphic microsatellite markers at 7 chromosomal regions frequently altered in breast cancer. The p53 gene mutations were also determined at exons 5 to 9. RESULTS: The frequency of complex fibroadenomas was similar in both groups (P =.42). Only in the case group did we observe proliferative lesions confined in fibroadenomas, including atypical ductal hyperplasia (2 cases), lobular neoplasia (3 cases), or low-grade ductal carcinoma in situ (2 cases). There is no significant morphological difference between the 2 groups. Neither microsatellite alterations nor p53 gene mutations are present in the fibroadenoma components. Loss of heterozygosity is found only in the epithelial component of the 2 ductal carcinomas in situ confined in fibroadenomas. CONCLUSIONS: Genetic alterations, which are most frequently involved in malignant breast carcinomas, are not present in fibroadenomas, regardless of their association with breast cancer or their histological complexity. These findings suggest that fibroadenomas are not associated with breast carcinogenesis. 相似文献
110.
New cytotoxic sesterterpenoids and norsesterterpenoids from two sponges of the genus Sarcotragus 总被引:1,自引:0,他引:1
Liu Y Mansoor TA Hong J Lee CO Sim CJ Im KS Kim ND Jung JH 《Journal of natural products》2003,66(11):1451-1456
New norsesterterpenoids (3 and 4), a sesterterpenoid (6), pyrroloterpenoids (7-10), and a stereoisomer of kurospongin (5) were isolated, along with known furanosesterterpenes (11-15), from two marine sponges of the genus Sarcotragus. The gross structures were established on the basis of NMR and MS analysis. The stereochemistry was defined by combined use of NMR and CD spectroscopy. The compounds were evaluated for cytotoxicity against five human tumor cell lines and were found to exhibit marginal to moderate activity. 相似文献