全文获取类型
收费全文 | 18703篇 |
免费 | 2303篇 |
国内免费 | 433篇 |
专业分类
耳鼻咽喉 | 46篇 |
儿科学 | 338篇 |
妇产科学 | 143篇 |
基础医学 | 978篇 |
口腔科学 | 902篇 |
临床医学 | 1288篇 |
内科学 | 1983篇 |
皮肤病学 | 436篇 |
神经病学 | 459篇 |
特种医学 | 1880篇 |
外国民族医学 | 12篇 |
外科学 | 897篇 |
综合类 | 2469篇 |
现状与发展 | 3篇 |
预防医学 | 1772篇 |
眼科学 | 144篇 |
药学 | 3677篇 |
29篇 | |
中国医学 | 1294篇 |
肿瘤学 | 2689篇 |
出版年
2024年 | 55篇 |
2023年 | 342篇 |
2022年 | 568篇 |
2021年 | 796篇 |
2020年 | 800篇 |
2019年 | 717篇 |
2018年 | 789篇 |
2017年 | 829篇 |
2016年 | 829篇 |
2015年 | 739篇 |
2014年 | 1434篇 |
2013年 | 1781篇 |
2012年 | 1209篇 |
2011年 | 1324篇 |
2010年 | 1027篇 |
2009年 | 882篇 |
2008年 | 894篇 |
2007年 | 822篇 |
2006年 | 673篇 |
2005年 | 647篇 |
2004年 | 510篇 |
2003年 | 427篇 |
2002年 | 405篇 |
2001年 | 333篇 |
2000年 | 285篇 |
1999年 | 256篇 |
1998年 | 210篇 |
1997年 | 190篇 |
1996年 | 152篇 |
1995年 | 150篇 |
1994年 | 132篇 |
1993年 | 127篇 |
1992年 | 100篇 |
1991年 | 108篇 |
1990年 | 98篇 |
1989年 | 107篇 |
1988年 | 79篇 |
1987年 | 68篇 |
1986年 | 61篇 |
1985年 | 98篇 |
1984年 | 77篇 |
1983年 | 46篇 |
1982年 | 58篇 |
1981年 | 45篇 |
1980年 | 40篇 |
1979年 | 41篇 |
1978年 | 15篇 |
1977年 | 22篇 |
1976年 | 13篇 |
1975年 | 11篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
41.
We reviewed the records of 110 consecutive patients with advanced-stage epithelial ovarian carcinoma treated at the Soroka Medical Center, Beer-Sheva, Israel, from 1961-1987. Twenty patients (18.1%) had optimal debulking at initial laparotomy, 30 patients (27.2%) had nonoptimal debulking at initial laparotomy, 20 patients (18.1%) had an "inoperable" disease at initial laparotomy, and 40 patients (36.3%) had such poorly written records that no information about the degree of resectability at initial laparotomy could be obtained. Four patients, in whom the residual tumor left at initial laparotomy had responded to chemotherapy, had a second laparotomy. In all four patients optimal debulking surgery at second laparotomy was easy to perform and was successful. The value of a second laparotomy after a few cycles of chemotherapy in order to optimally debulk the residual tumor left at initial laparotomy is discussed. It is concluded that a second attempt of debulking surgery after chemotherapy has a respectable place in the management of patients with advanced-state epithelial ovarian carcinoma, but further research is needed. 相似文献
42.
Chien Yie W. Chien Te-yen Bagdon Robert E. Huang Yih C. Bierman Robert H. 《Pharmaceutical research》1989,6(12):1000-1010
Several transdermal contraceptive device (TCD) formulations were developed to provide a dual-controlled transdermal delivery of levonorgestrel (LN), a potent progestin, and 17-estradiol (E2), a natural estrogen. Using a sensitive HPLC method, the in vitro release and skin permeation profiles of LN and E2 from various TCD formulations were simultaneously characterized in the hydrodynamically well-calibrated Valia–Chien skin permeation cells and both were found to follow zero-order kinetics. The rates of drug release and skin permeation were observed to vary significantly depending upon some formulation parameters. Six-month stability studies were performed on seven formulations at room and elevated temperatures (37 and 45°C), and two (Formulations 4 and 5) were found to be acceptable, based on drug recovery, release rate, and skin permeation rate data. Judging from the 6-month accelerated stability studies, it is projected these two formulations will have shelf-life of at least 2 years. As a result of development of an efficient manufacturing process, Formulation 4 was selected for further evaluation. One-week primary skin irritation evaluation in 6 rabbits indicated that Formulation 4 is nonirritating, and it was thus selected for Phase I clinical bioavailability/dose proportionality studies in 12 healthy female volunteers of child-bearing age. Results of pharmacokinetic and pharmacodynamic analyses demonstrated that it is capable of achieving and maintaining a steady-state serum level of LN throughout the 3-week treatment period by weekly applications of one or two TCD patches (10 or 20 cm2). A dose proportionality was obtained in the serum drug levels, daily dose delivered, and contraception efficacy. An excellent correlation was obtained for the rates of transdermal delivery determined by the in vitro studies using human cadaver skin, the in vivo studies in rabbits, and the clinical studies in living subjects. 相似文献
43.
The effect of acute infection of mice with lactic dehydrogenase virus (LDV) on two major functions of peritoneal macrophages was tested. Using a macrophage-dependent T cell proliferative assay to test the antigen-presenting capacity of LDV-infected macrophages we found that LDV impairs the capacity of antigen-presenting cells to trigger memory T lymphocytes. Endocytosis of antigen by LDV-infected macrophages was similar to that of uninfected cells. In addition, the proportion of intracellular antigen versus membrane-bound antigen in LDV-infected cells were similar to that observed in uninfected mice. It appears therefore, that the impaired immunogenic effect of LDV-infected macrophages results from reduced immunogenicity of the membrane-bound antigen.Testing the phagocytic activity of peritoneal macrophages we found that the uptake of radiolabeled antibody-coated sheep erythrocytes or bacteria (E. coli) by infected cells was similar to that by uninfected macrophages. In addition, LDV failed to affect the ability of peritoneal macrophages in a nitroblue tetrazolium reduction reaction which serves as an alternative parameter for measuring phagocytic activity. Our results support the assumption that LDV, which probably propagates in the cells of the reticuloendothelial system, impairs some of the immunogenic functions of macrophages and thereby affects macrophage-dependent immune responses. 相似文献
44.
目的:通过测量不同滤过条件下,体模入射剂量随滤过条件的变化确定高千伏X线摄影时的最佳附加滤过。材料与方法:利用X线剂量仪测量不同Al滤过时对应体模表面剂量的变化。结果与结论:通过适当增加附加滤过可以合理降低被检者皮肤剂量,120kV摄影时,附加滤过2.5mmAl是恰当的。 相似文献
45.
Diane J. Pincus MD Teresa R. Humeston BS Richard J. Martin MD 《The Journal of allergy and clinical immunology》1997,100(6):771-774
Background: Chronotherapy studies with inhaled corticosteroids have shown optimal therapeutic benefit when steroids are administered four times per day (QID) or once daily at 3 PM.Objective: This study evaluated whether more convenient once-daily dosage times (8 AM and 5:30 PM) produce improvement in asthma equivalent to QID.Methods: Efficacy outcome measures included FEV1, peak expiratory flow rates, bronchial responsiveness, use of β2-agonists, nocturnal awakenings, and responses to a quality of life questionnaire. Systemic effects were blood eosinophil count, cortisol level, 24-hour urinary cortisol, and evaluation for oral candidiasis and dysphonia.Results: Baseline measurements for all three treatment groups were similar. For morning peak expiratory flow rate, significant improvement was seen for the QID group (p = 0.001) and the 5:30 PM group (p = 0.003), but not the 8 AM group (p = 0.75). For evening peak expiratory flow rate, significant improvement was seen for the QID group (p = 0.005) and the 5:30 PM group (p = 0.01), but not for the 8 AM group (p = 0.47). There were significant improvements in all other outcome variables for each group except PC20. There was a significant improvement in PC20 only in the QID group. The systemic effects of the three regimens were comparable.Conclusion: Dosing of inhaled steroid at 5:30 PM had no increased systemic effects and produced efficacy similar to QID dosing. Dosing at 8 AM did not produce results consistently comparable to QID dosing. Optimal once-daily dosing of inhaled steroid is between 3 PM and 5:30 PM. 相似文献
46.
Lienou C Taziebou F-X Etoa B Nkegoum C A Pieme D PD Dzeufiet 《African journal of traditional, complementary, and alternative medicines》2007,4(2):127-134
This study was designed to evaluate the toxicity of the aqueous extract of Aspilia africana leaves. Oral doses of 500 mg/kg and 1000 mg/kg were administered for 28 days to rats after every 2 days for sub-acute toxicity. For acute toxicity, 5 doses of 2, 4, 8, 12 and 16g/Kg body weight were investigated in mice. The control groups consisted of mice or rats administered with distilled water. The signs of toxicity fluctuated lightly from one mammal to another throughout the experiment. The liver, kidneys and heart weight of rats revealed no significant differences between the test groups and the control. The results indicated that the medium lethal dose (LD50) was found to be greater in females than males with an average of 6.6g/Kg body weight for both sexes. Regardless of the significant differences observed at certain points in some biochemical parameters (ALT, AST, ALP, Creatinine and Glutathione); none showed any linear dose responsiveness. On the other hand, most of the parameters investigated were found to be gender dependent. These results suggested that A Africana can be classified among substances with low toxicity. 相似文献
47.
目的:目前,国内X(γ)刀的国家检定规程正在起草之中,本文的目的是为X(γ)刀剂量测量提供合理的设备与吸收剂量计算方法。材料与方法:利用德国PTW-UNIDOS剂量仅与有效体积为0.015cc的针尖电离室及自制的小体积半导体探测器相匹配,在160mm直径的有机玻璃球形模体内测量X(γ)刀的输出吸收剂量,并验证其治疗计划的实际输出剂量,得到较满意的结果。结论:为了保证剂量的准确度,X(γ)刀治疗计划系统的实际输出剂量应定期在现场测量与验证,所用探测器的直径应小于射野直径的1/2,小灵敏体积的半导体探测器适宜X(γ)刀小野(如:Ф4mm)的测量。 相似文献
48.
Pnina Fishman Emily Falach-Vaknin Benjamin Sredni Piere Luigi Meroni Angela Tincani Dror Dicker Yehuda Shoenfeld 《American journal of reproductive immunology (New York, N.Y. : 1989)》1996,35(2):80-84
PROBLEM: Previously we reported on the generation of experimental anti-phospholipid syndrome (APS) in mice. These models were employed to evaluate the efficacy of various novel therapeutic modalities including interleukin-3 (IL-3) and low dose aspirin. The efficacy of the latter was found to be interrelated. Low dose aspirin is capable of inhibiting the activity of the enzyme cyclooxygenase which is responsible for the metabolism of arachidonic acid towards the production of prostaglandins. This shifts the metabolism of arachidonic acid to the other pathway and leads to an overproduction of leukotrienes. The leukotrienes act as stimulators of IL-3 production, a positive cytokine in pregnancy which enhances placental and fetal development. In the current study we evaluated the IL-3 levels in pregnant women with APS and expanded our knowledge on the interrelationships between aspirin, arachidonic acid metabolites and IL-3 in the human system. METHODS: IL-3 levels were recorded in the serum of pregnant women with APS and compared to a control pregnant group. In addition peripheral blood mononuclear cells from healthy subjects were incubated with different concentrations of aspirin or with arachidonic acid metabolites (Leukotriene B4, C4 or PGE2), and IL-3 production in the culture fluids was evaluated. RESULTS: Serum level of IL-3 in pregnant patients with primary APS, APS secondary to SLE and SLE was lower in comparison to the control group. The in vitro studies revealed that only low dose aspirin (10 mg/μl) stimulated IL-3 production while higher doses of the drug failed to induce the cytokine generation. Leukotriene B4 and C4 were stimulatory whereas PGE2 acted as inhibitor of IL-3 production. CONCLUSIONS: The serum level of IL-3 is decreased to pregnant women with primary or secondary APS. Low dose aspirin is capable of stimulating EL-3 production in vitro most probably through an elevation of leukotriene production, which may explain its beneficial activity in preventing the manifestations of APS. 相似文献
49.
R. Metz M. Delgado R. Keiling P. Cappelaere J. P. Armand G. Prevot J. L. Misset J. Grimbert G. Mathe 《Investigational new drugs》1985,3(2):163-166
Summary In our wide experience of treating advanced breast carcinoma with chemotherapy, the combination of doxorubicin (DOX), vincristine (VCR), cyclophosphamide (CPM) and fluorouracil (FU) gave a complete plus partial response rate of over 60%, with 100% alopecia and frequent cardiac toxicity depending on total dose.After the EORTC Clinical Screening Group phase II trial we have conducted an expected difference method comparative phase II trial using the combination DOX, VCR, CPM, FU and the combination of MTX (10mg/m2), VCR, CPM and FU on a population of 50 breast carcinoma patients similar to those taking part in the first study.The reasons for similarity of action will be presented and discussed. 相似文献
50.
R Arriagada H Mouriesse D Sarrazin R M Clark G Deboer 《International journal of radiation oncology, biology, physics》1985,11(10):1751-1757
This retrospective study involved 463 breast cancer patients treated by radiotherapy alone at the Princess Margaret Hospital and at the Institut Gustave-Roussy. These patients either had operable tumors, but were unfit for general anesthesia, or had inoperable tumors due to local contraindications to surgery. Results were analyzed according to tumor response, local recurrence rate, tumor size, tumor fixation, nodal fixation and tumor dose. Conventional statistical analysis of local control showed two significant factors: tumor dose and tumor size. Multivariate analysis permitted to define an "individual risk" (IR) of local recurrence according to three independent factors: tumor size, tumor fixation, and nodal fixation. It was shown that the IR was a good prognostic factor for local control. Increase in tumor dose gave a similar effect in the local recurrence relative risk for all the IR groups. According to the slope of the dose-effect curve, it was deduced that a dose increase of 15 Gy can decrease the relative risk of local recurrence 2-fold. In fact, it was shown that tumor dose was the most significant independent factor on local control, able to produce up to a 10-fold increase compared to 2-fold decrease for tumor size. If the IR of local recurrence is known, a theoretical predictive value on local control, taking into account the tumor dose, can be determined according to the present data. 相似文献