全文获取类型
收费全文 | 89315篇 |
免费 | 7997篇 |
国内免费 | 177篇 |
专业分类
耳鼻咽喉 | 1061篇 |
儿科学 | 2645篇 |
妇产科学 | 2380篇 |
基础医学 | 13250篇 |
口腔科学 | 1854篇 |
临床医学 | 11607篇 |
内科学 | 15428篇 |
皮肤病学 | 1394篇 |
神经病学 | 8422篇 |
特种医学 | 3080篇 |
外国民族医学 | 1篇 |
外科学 | 10570篇 |
综合类 | 1401篇 |
现状与发展 | 1篇 |
一般理论 | 64篇 |
预防医学 | 9782篇 |
眼科学 | 1921篇 |
药学 | 6334篇 |
2篇 | |
中国医学 | 121篇 |
肿瘤学 | 6171篇 |
出版年
2022年 | 627篇 |
2021年 | 1651篇 |
2020年 | 1011篇 |
2019年 | 1670篇 |
2018年 | 1978篇 |
2017年 | 1567篇 |
2016年 | 1624篇 |
2015年 | 1769篇 |
2014年 | 2453篇 |
2013年 | 3441篇 |
2012年 | 5237篇 |
2011年 | 5409篇 |
2010年 | 2927篇 |
2009年 | 2547篇 |
2008年 | 4553篇 |
2007年 | 4835篇 |
2006年 | 4586篇 |
2005年 | 4655篇 |
2004年 | 4201篇 |
2003年 | 3905篇 |
2002年 | 3810篇 |
2001年 | 2092篇 |
2000年 | 2126篇 |
1999年 | 1965篇 |
1998年 | 1099篇 |
1997年 | 897篇 |
1996年 | 829篇 |
1995年 | 840篇 |
1994年 | 696篇 |
1993年 | 681篇 |
1992年 | 1577篇 |
1991年 | 1461篇 |
1990年 | 1425篇 |
1989年 | 1347篇 |
1988年 | 1233篇 |
1987年 | 1221篇 |
1986年 | 1109篇 |
1985年 | 1103篇 |
1984年 | 880篇 |
1983年 | 772篇 |
1982年 | 563篇 |
1981年 | 532篇 |
1980年 | 535篇 |
1979年 | 807篇 |
1978年 | 625篇 |
1977年 | 516篇 |
1974年 | 555篇 |
1973年 | 551篇 |
1972年 | 550篇 |
1971年 | 511篇 |
排序方式: 共有10000条查询结果,搜索用时 312 毫秒
51.
OBJECTIVES: To pilot the acceptability and feasibility of clinical audit in free and pedicled flap reconstruction. To establish a baseline flap failure rate in participating units, so that a sample size calculation could be performed for future national audit. METHODS: A proforma was piloted over a 3-month period in four participating units, during which time data on 93 reconstructive procedures involving free and pedicled flaps was collected. The patients included those where large transfers of tissue were required such as for coverage of grade IIIb compound tibial fractures and breast reconstruction after mastectomy, and also smaller flap transfers such as after skin cancer excision. RESULTS: The proforma was found to be acceptable to clinicians and the feasibility of the data collection process was established. Overall there was a total flap survival of 89% and secondary operations to the donor or recipient sites were required in 11% of patients. CONCLUSIONS: This study demonstrates the feasibility of comparative audit for free and pedicled flap procedures using the methods proposed. Based on the incidence of flap failure observed in this pilot study, at least 18 months of prospective data collection on consecutive patients is required to fulfil the statistical requirements of comparative audit. The establishment of a routinely collected minimum dataset is proposed as one means of meeting these requirements. 相似文献
52.
Outcomes at 3 years of a prospective pilot study of Campath-1H and sirolimus immunosuppression for renal transplantation 总被引:2,自引:0,他引:2
Rolf N. Barth Christina A. Janus Christine A. Lillesand Nancy A. Radke John D. Pirsch Bryan N. Becker Luis A. Fernandez L. Thomas Chin Yolanda T. Becker Jon S. Odorico Anthony M. D''Alessandro Hans W. Sollinger Stuart J. Knechtle 《Transplant international》2006,19(11):885-892
Campath-1H (alemtuzumab) induction was used for renal transplantation in combination with sirolimus as immunosuppression. We previously reported a high (28%) rate of early rejection with this regimen, and now report 3-year outcomes. Twenty-nine patients were recipients of either deceased donor or non-HLA (Human Leukocyte Antigen) identical living donor primary renal allografts. Clinical parameters including infection, malignancy, kidney function, and kidney histology were followed prospectively for 3 years. Three-year cumulative graft and patient survival were 96% and 100%, respectively. Twenty patients were maintained on steroid-free immunosuppressive regimens, and 15 patients were maintained on monotherapy for immunosuppression (12 on sirolimus). No serious infectious complications were observed and two patients developed basal cell skin cancer. The 3-year results of our initial pilot study demonstrate good graft (96%) and patient (100%) outcomes. Campath-1H induction has yielded a high proportion of patients maintained on immunosuppressive monotherapy (57%) without serious infectious- and no malignancy-related complications. The reported regimen yielded novel insights into both Campath-1H and sirolimus therapy in renal transplantation. Because of the higher incidence of early rejection, we recommend a modified strategy of immunosuppression including a brief course of a calcineurin inhibitor. 相似文献
53.
54.
Alex N. Bullock Julia Henckel Brian S. DeDecker Christopher M. Johnson Penka V. Nikolova Mark R. Proctor David P. Lane Alan R. Fersht 《Proceedings of the National Academy of Sciences of the United States of America》1997,94(26):14338-14342
Some 50% of human cancers are associated with mutations in the core domain of the tumor suppressor p53. Many mutations are thought just to destabilize the protein. To assess this and the possibility of rescue, we have set up a system to analyze the stability of the core domain and its mutants. The use of differential scanning calorimetry or spectroscopy to measure its melting temperature leads to irreversible denaturation and aggregation and so is useful as only a qualitative guide to stability. There are excellent two-state denaturation curves on the addition of urea that may be analyzed quantitatively. One Zn2+ ion remains tightly bound in the holo-form of p53 throughout the denaturation curve. The stability of wild type is 6.0 kcal (1 kcal = 4.18 kJ)/mol at 25°C and 9.8 kcal/mol at 10°C. The oncogenic mutants R175H, C242S, R248Q, R249S, and R273H are destabilized by 3.0, 2.9, 1.9, 1.9, and 0.4 kcal/mol, respectively. Under certain denaturing conditions, the wild-type domain forms an aggregate that is relatively highly fluorescent at 340 nm on excitation at 280 nm. The destabilized mutants give this fluorescence under milder denaturation conditions. 相似文献
55.
56.
57.
In the doubly-labelled water (2H2(18)O) method for the measurement of carbon dioxide production rate in man, single exponential disappearance curves for 2H2O and H2(18)O in body water are used; the precision with which the slopes and intercepts of the curves are estimated determines the precision of the estimate of carbon dioxide production rate. In studies with infants, and in computer simulations, the effect of different experimental regimes on the overall precision of the carbon dioxide production estimate was investigated. When the number of data points used was progressively reduced by shortening the total observation period from 7 d (about 3 biological half-lives for the isotopes) to 1 d there was a deleterious effect on precision and in the infants there was an upward bias in the values for carbon dioxide production. When the number of data points was reduced by removing points from the middle of the exponential curves with the maintenance of the 7-d experimental period, precision was also reduced but by less than in the former procedure and there were no consistent trends in the average values for carbon dioxide production. 相似文献
58.
B. A. Johnson Donald R. Jasinski Gantt P. Galloway Henry Kranzler Robert Weinreib Raymond F. Anton Barbara J. Mason Michael J. Bohn Helen M. Pettinati Richard Rawson Christopher Clyde 《Psychopharmacology》1996,128(2):206-215
Four hundred and twenty-three alcohol dependent subjects were enrolled into a 12-week randomized, double-blind, placebo-controlled
study to determine the safety and efficacy of the 5-HT2 receptor antagonist, ritanserin (2.5 mg/day or 5 mg/day), in reducing alcohol intake and craving. All subjects received 1
week of single-blind placebo prior to randomization into the 11-week double-blind phase. Additionally, all subjects received
weekly individual sessions of manual-guided cognitive-behavioral therapy. Comparing the single-blind period with endpoint,
there was approximately a 23% reduction in drinks/day; 34% fall in the total number of drinking days/week; 22% decrease in
drinks/drinking day; and a 37% diminution in alcohol craving for all treatment groups. All treatment groups experienced a
beneficial clinical outcome as assessed by the Clinical Global Impression Scale. There was, however, no significant difference
between treatment groups on any of these measures of alcohol drinking, craving, or clinical outcome. Subjects were of relatively
high social functioning at baseline, and this did not change significantly during treatment. Treatment groups did not differ
significantly on either medication compliance or reported adverse events. Ritanserin treatment was associated with a dose-related
prolongation of subjects’ QTc interval recording on the electrocardiogram. These results suggest that alcohol dependent subjects
can show marked clinical improvement within a structured alcohol treatment program. These findings do not support an important
role for ritanserin in the treatment of alcohol dependence.
Received: 30 April 1996/Final version: 3 July 1996 相似文献
59.
Juin Fok-Seang Linda C. Smith-Thomas Sally Meiners Elizabeth Muir Jian-Sheng Du Elizabeth Housden Alan R. Johnson Andreas Faissner Herbert M. Geller Roger J. Keynes John H. Rogers James W. Fawcett 《Brain research》1995,689(2):207
The adult mammalian central nervous system (CNS) lacks the capacity to support axonal regeneration. There is increasing evidence to suggest that astrocytes, the major glial population in the CNS, may possess both axon-growth promoting and axon-growth inhibitory properties and the latter may contribute to the poor regenerative capacity of the CNS. In order to examine the molecular differences between axon-growth permissive and axon-growth inhibitory astrocytes, a panel of astrocyte cell lines exhibiting a range of axon-growth promoting properties was generated and analysed. No clear correlation was found between the axon-growth promoting properties of these astrocyte cell lines with: (i) the expression of known neurite-outgrowth promoting molecules such as laminin, fibronectin andN-cadherin; (ii) the expression of known inhibitory molecules such tenascin and chondroitin sulphate proteoglycan; (iii) plasminogen activator and plasminogen activator inhibitor activity; and (iv) growth cone collapsing activity. EM studies on aggregates formed from astrocyte cell lines, however, revealed the presence of an abundance of extracellular matrix material associated with the more inhibitory astrocyte cell lines. When matrix deposited by astrocyte cell lines was assessed for axon-growth promoting activity, matrix from permissive lines was found to be a good substrate, whereas matrix from the inhibitory astrocyte lines was a poor substrate for neuritic growth. Our findings, taken together, suggest that the functional differences between the permissive and the inhibitory astrocyte cell lines reside largely with the ECM. 相似文献