首页 | 本学科首页   官方微博 | 高级检索  
文章检索
  按 检索   检索词:      
出版年份:   被引次数:   他引次数: 提示:输入*表示无穷大
  收费全文   155105篇
  免费   9190篇
  国内免费   1411篇
耳鼻咽喉   2501篇
儿科学   2493篇
妇产科学   2586篇
基础医学   24097篇
口腔科学   3560篇
临床医学   14290篇
内科学   28669篇
皮肤病学   4635篇
神经病学   12375篇
特种医学   8519篇
外科学   20904篇
综合类   1110篇
现状与发展   3篇
一般理论   42篇
预防医学   8060篇
眼科学   4086篇
药学   13745篇
中国医学   1635篇
肿瘤学   12396篇
  2023年   1094篇
  2022年   3164篇
  2021年   5158篇
  2020年   2517篇
  2019年   3604篇
  2018年   4473篇
  2017年   3532篇
  2016年   4551篇
  2015年   6277篇
  2014年   7515篇
  2013年   8836篇
  2012年   13158篇
  2011年   12731篇
  2010年   7320篇
  2009年   6305篇
  2008年   9062篇
  2007年   8678篇
  2006年   7861篇
  2005年   7336篇
  2004年   6388篇
  2003年   5725篇
  2002年   5007篇
  2001年   3918篇
  2000年   3570篇
  1999年   2857篇
  1998年   1161篇
  1997年   913篇
  1996年   747篇
  1995年   644篇
  1994年   553篇
  1993年   454篇
  1992年   1126篇
  1991年   1014篇
  1990年   970篇
  1989年   857篇
  1988年   763篇
  1987年   756篇
  1986年   569篇
  1985年   586篇
  1984年   436篇
  1983年   335篇
  1982年   236篇
  1981年   253篇
  1980年   210篇
  1979年   364篇
  1978年   278篇
  1977年   189篇
  1976年   187篇
  1975年   190篇
  1974年   204篇
排序方式: 共有10000条查询结果,搜索用时 0 毫秒
61.
Chiropractic practitioners with accredited qualifications should have the right to diagnose, the right to operate diagnostic imaging machines, and the right to the title doctor and Yee San. This paper reviews chiropractic practice in Hong Kong as well as laws and provisions of the health professions namely Chiropractors Registration Ordinance, Medical Registration Ordinance, Dentists Registration Ordinance, Radiation Ordinance, and the provisions of codes of practice of Medical Laboratory Technologists and Radiographers. The need for amendments of relevant sections of health laws and provisions, which concern chiropractic rights, chiropractic practice, and clinical research of mechanical neuromusculoskeletal disorders is discussed. Patient privileges relevant to chiropractic practice are proposed. The Chinese title Yee San or Yee and the English title Doctor are generic terms. Hence, legally “Yee San” and “Doctor” should not be coined by medical practitioners and vice versa. Diagnostic imaging and laboratory procedures are essential for differential diagnosis of neuromusculoskeletal disorders, which may indicate or contraindicate the application of manipulation, and hence are essential for chiropractic practice and clinical research. Proposed amendments of the listed sections of the ordinances and provisions are also outlined.  相似文献   
62.
Critical to the proper management of pyoderma gangrenosum are correct diagnosis, identification and treatment of any underlying disorder, and the proper choice of topical and systemic therapy. Many agents are available for the treatment of pyoderma gangrenosum. We review the current therapeutic options, their efficacy and side effects, and we offer some guidelines for their proper selection.  相似文献   
63.
Summary Gene therapy is the delivery of genetic material to specific cell types of an organism to alter its physiology or function. This technology is being explored as a means of treating diseases caused by deficiencies of hepatic gene products. The two diseases being used as models for hepatic gene therapy are classical phenylketonuria (PKU) and haemophilia B. Vectors derived from adenoviruses can be used to completely correct these diseases in animal models. The phenotypic correction generated in these studies is transient, and cannot be duplicated by vector readministration. The transient nature of transgene expression results from the destruction of the virally-transduced cells by a cellular immune response directed against the late viral gene products that are also expressed in the target cells. The inability to repeatedly administer virus is caused by a humoral immune response directed against viral proteins present at the time of infusion. If the host immune response is suppressed, transgene expression can persist for 6 months or more. These findings suggest that host immunomodulation in combination with further modification of the adenoviral vector to reduce or eliminate late viral gene expression may permit long-term expression of potentially therapeutic gene products in mammalian liver.  相似文献   
64.
PURPOSETo evaluate the efficacy, safety, and results of direct thrombolytic therapy in intracranial dural sinus thrombosis by infusion of alteplase (recombinant tissue plasminogen activator).METHODSNine patients were treated during a 2-year period for intracranial dural sinus thrombosis. A microcatheter was placed directly into the thrombus in the dural sinus via the transfemoral route. Thrombolysis was initiated with a rapid injection of 10 mg of alteplase over 10 minutes, followed in 3 hours by a continuous infusion of 50 mg, then a continuous infusion at 5 mg per hour until complete thrombolysis or a total dose of 100 mg per day had been reached. Repeat thrombolysis was tried the following day if complete recanalization did not occur at 100 mg per day.RESULTSSuccessful recanalization with improvement of symptoms was achieved in all cases. Time required for complete thrombolysis was between 8 and 43 hours. The total dose of alteplase ranged from 50 to 300 mg. Complications of a small intrapelvic hemorrhage and oozing at a femoral puncture site occurred in separate cases, but were not related to the amount of infused alteplase. MR venograms obtained 1 to 4 weeks after the procedure showed no evidence of reocclusion of the dural sinuses.CONCLUSIONDirect fibrinolytic therapy with alteplase is safe, fast, and effective in treating dural sinus thrombosis. However, to prevent hemorrhagic complications, further studies are required to determine its optimal dose and proper rate of administration.  相似文献   
65.
Transforming growth factor-β1 (TGF-β1) is known to be a potent growth inhibitor for many cell types, including most epithelial cells. In skin keratinocytes, TGF-β1 has been shown to inhibit growth and to rapidly reduce c-mycexpression. However, the molecular mechanism of TGF-β1 action on cell growth of cervical carcinoma has not yet been elucidated. We thus assessed the effect of TGF-β1 on the growth of cervical carcinoma cell lines. Two cervical squamous carcinoma cell lines, CUMC-3 and CUMC-6, were incubated with varying concentrations of TGF-β1, and growth inhibition was evaluated with tetrazolium-based colorimetric assay. After culture in TGF-β1 for 24 h, inhibition of growth was detected in a dose-dependent manner at concentrations of 0.1–10 ng/ml in both cell lines. This effect of TGF-β1 on cultured carcinoma cells was associated with apoptotic process including oligonucleosomal ladder DNA and apoptotic body formations. Northern blot analysis revealed c-mycmRNA expression was suppressed by 10 ng/ml of TGF-β1 following 3 h of treatment in both cell lines. Western blot analysis showed that the level of p27Kip1protein was increased after TGF-β1 treatment in both cell lines. These results suggest that the mechanisms by which TGF-β1 inhibits the growth of cervical carcinoma are complex and may include effects on down-regulation of c-mycgene, and overexpression of p27Kip1protein.  相似文献   
66.
Purpose. To determine whether the non-toxic pentameric B subunit of Cholera toxin (CTB) binding to ganglioside GM1 on both the lipid vesicles and epithelial cells may provide a means to target lipid vesicles to mucosal cells expressing surface GM1. Methods. Sonicated lipid vesicles containing ganglioside GM1 were prepared. Inter-vesicle cross-linking due to pentameric CTB binding to these GM1 vesicles was determined with a sub-micron particle analyzer. Association of CTB to GM1 vesicles was analyzed with continuous sucrose gradient centrifugation. CTB-mediated binding of GM1 vesicles to human mucosal epithelial cells (Caco-2 and HT-29), mucous membranes of mouse trachea, and nasal tissues were detected with fluorescent labeled vesicles. Results. An increase in lipid particle size due to binding of CTB to lipid vesicles and inter-vesicles cross-linking was detected. At a 30-to-1 mole ratio of membrane-bound GMl-to-CTB, optimum increase in GM1 vesicle aggregation, was detected. Under such conditions, all the added CTB molecules were associated with GM1 vesicles. Time course analysis showed that inter-vesicles cross linking by CTB was detectable within 10 min. and reached a maximum value at 60 min. CTB associated GM1-vesicles bind to mucosal epithelial cells HT-29 and Caco-2 with similar affinity [Kd = 7.8 × 10–4 M lipid (Caco-2) and 7.6 × 10–4 M lipid (HT-29)]. GM1 mediated binding specificity was demonstrated by blocking with anti-GMl antibody and the insignificant degree of CTB-associated GM1 vesicle binding to GM1 deficient C6 cells. Conclusions. The CTB-mediated GM1 binding to multiple membrane surfaces provides selective localization of GM1 vesicles to GM1 expressing mucosal cells and tissues. The strategy may be useful in localizing drugs and proteins to gut and respiratory tract mucosa.  相似文献   
67.
The study aimed to compare the longitudinal assessment of autonomic nerve function by computerized infrared pupillometry and standard cardiovascular tests in adolescents with diabetes. Adolescents (n = 150) were assessed at two time points (T1 and T2). The median time interval between assessments was 1.5 (range 0.9–3) years. At T1 the median age was 14.5 (range 8.3–19.5) years and the median duration was 6.5 (range 1.1–16) years. The pupillary variables assessed included the resting pupil diameter, the maximum constriction velocity, and the reflex amplitude of constriction. Heart rate reflexes were assessed in response to deep breathing, the Valsalva manoeuvre, and on standing from a lying position (30/15 ratio). Between visits there was a significant decrease in maximum constriction velocity (6.0 mm s?1 vs 6.3 mm s?1, p = 0.0001) and resting pupil diameter (6.2 mm vs 6.3 mm, p = 0.001). At reassessment pupillary abnormalities increased from 32 (21 %) to 45 (30%), with 17 (54 %) of the initial abnormalities persisting. Adolescents with abnormally slow maximum constriction velocity compared to those with normal maximum constriction velocity had a higher glycated haemoglobin (HbA1c%) at T2 (p = 0.02) and between assessments (p = 0.01). Cardiovascular test abnormalities did not increase between visits and the persistence of initial abnormalities was low (21 %). In summary, pupillometry appears a more sensitive test of autonomic nerve dysfunction in adolescents with diabetes than assessment of cardiovascular reflexes.  相似文献   
68.
Epicardial antiarrhythmic drug administration was studied as a therapeutic approach for experimental ventricular tachycardia (VT) in an open-chest dog model. Lidocaine-polyurethane matrices (28%, w/w) were formulated as a model system. Matrices were placed on the left ventricular epicardium in each of 23 anesthetized open-chest dogs with ouabain-induced VT, to evaluate effectiveness in restoring sinus rhythm. Conversion occurred in all animals treated with matrices containing 300 mg or more of lidocaine after 1.5 to 7.0 min. The matrix lidocaine content correlated linearly with the time required for conversion to sinus rhythm (r = 0.75, P = 0.0002); irrespective of matrix size the myocardial/plasma lidocaine ratio was 20.1 ± 4.2 (mean ± SD) at the time of conversion. In a separate series of five dogs without ventricular tachycardia, systolic wall thickening measured with sonomicrometers after 5 min of controlled-release lidocaine administration (500- to 1000-mg matrix lidocaine content, 7.48 ± 3.49-mg/kg dose) was only minimally diminished (–14.1%) and this effect was observed only at the site of matrix placement on the anterior-apical epicardium. In contrast, intracoronary injection of 0.3 or 1.0 mg/kg of lidocaine-HCl resulted in complete elimination of wall thickening or replacement by systolic thinning. Thus epicardial administration of lidocaine from polyurethane matrices was an effective means of treating ouabain-induced ventricular tachycardia. Regional myocardial function in the vicinity of the matrices was modified to a very limited degree, supporting the view that the matrices can be used safely, without serious risk to ventricular contractile performance.  相似文献   
69.
The epoxyalkanoyl derivatives were designed and synthesized as ACE inhibitors. Coupling of unsaturated carboxylic acids with amino acids and following epoxidation with dimethyldioxirane gave the epoxyalkanoyls with high yield. The inhibitory activity of synthesized compounds on angiotensin converting enzyme was IC50 values of 0.06≈5.5 μM.  相似文献   
70.
A 45-year-old man was referred to our department in March of 1989. Physical examination showed erythroderma, palmo-plantar hyperkeratosis, generalized lymphadenopathy, hepatosplenomegaly, and leukemic manifestation. The lymphocyte count in the peripheral blood before treatment was 1.7 × 104 cells/mm3. Atypical lymphocytes such as flower cells and lobulated cells were seen in the peripheral blood. A sample excised from a lymph node showed immunoblastic, pleomorphic T cells by a modified classification scheme of the Working Formulation. A high level of serum LDH was detected (2.1 times the upper normal limit). Anti HTLV-1 antibody was also detected in the serum. The atypical lymphocytes were positive for CD3, CD4, CD5, CD7 and HLA-DR, and negative for CD8. Thus, the clinical, pathologic and immunologic features were those of typical acute-type ATL. The patient was treated with VEPA-M for three months starting in March of 1989. Because of poor response, the patient was then treated with MACOP-B, M-FEPA, and VEPP-B for about one year from June of 1989 and has been free of disease up to the time of writing, March of 1993.  相似文献   
设为首页 | 免责声明 | 关于勤云 | 加入收藏

Copyright©北京勤云科技发展有限公司  京ICP备09084417号