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   383312篇
  免费   24447篇
  国内免费   2855篇
耳鼻咽喉   5192篇
儿科学   8275篇
妇产科学   10132篇
基础医学   53618篇
口腔科学   11878篇
临床医学   30472篇
内科学   79671篇
皮肤病学   8593篇
神经病学   27593篇
特种医学   14051篇
外国民族医学   82篇
外科学   61182篇
综合类   9969篇
现状与发展   1篇
一般理论   64篇
预防医学   17557篇
眼科学   9547篇
药学   31196篇
  1篇
中国医学   2204篇
肿瘤学   29336篇
  2021年   2713篇
  2019年   2796篇
  2018年   4612篇
  2017年   3516篇
  2016年   3617篇
  2015年   4153篇
  2014年   5810篇
  2013年   7513篇
  2012年   10273篇
  2011年   10521篇
  2010年   6317篇
  2009年   5968篇
  2008年   9655篇
  2007年   10547篇
  2006年   10411篇
  2005年   9505篇
  2004年   8977篇
  2003年   8750篇
  2002年   8400篇
  2001年   28359篇
  2000年   28912篇
  1999年   23758篇
  1998年   5217篇
  1997年   4281篇
  1996年   3873篇
  1995年   3515篇
  1994年   3139篇
  1993年   2865篇
  1992年   16120篇
  1991年   14870篇
  1990年   14201篇
  1989年   14022篇
  1988年   12626篇
  1987年   12096篇
  1986年   11143篇
  1985年   10361篇
  1984年   6940篇
  1983年   5626篇
  1982年   2734篇
  1979年   5499篇
  1978年   3361篇
  1977年   2979篇
  1975年   2654篇
  1974年   3072篇
  1973年   2874篇
  1972年   2843篇
  1971年   2782篇
  1970年   2522篇
  1969年   2557篇
  1968年   2256篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
992.
993.
994.
Buserelin, a luteinizing hormone releasing hormone agonist was administered nasally in doses of 900 micrograms daily to inhibit the ovarian cycle. Of 16 patients recruited, ten completed the treatment. Daily symptoms were measured on the Visual Analogue Scale and Trigg's trend analysis utilized for the analysis. The peak severity of symptoms (ESAmax) and the maximum global scores (Gmax) reduced on buserelin treatment. The minimum global scores (Gmin) and the minimum score for each symptom (ESAmin) increased, suggesting worsening of underlying symptoms. The difference between ESAmax and ESAmin (ESAdelta) and Gmax and Gmin (Gdelta) were calculated to determine the degree of symptom change. The delta scores for symptoms of depression, bloatedness and breast symptoms, and Gdelta were significantly reduced (p less than 0.05) on buserelin, whilst the latter significantly worsened in the follow-up months. Side-effects may limit the place of buserelin in the long-term treatment of premenstrual syndrome, although combination of additional hormonal treatment may facilitate long-term treatment.  相似文献   
995.
A case of Plasmodium falciparum malaria is reported in a 25-year-old pregnant woman with a history of three previous cesarean sections. She developed premature precipitate labor which was complicated by stillbirth, uterine rupture, bladder and vaginal tears necessitating hysterectomy.  相似文献   
996.
The generation of monoenergetic or quasimonoenergetic x-ray spectra has been accomplished by several methods including the use of K-edge filtration, characteristic radiation, crystal monochromators, and multilayer mirrors. In this paper some practical questions are discussed regarding the possibility of obtaining narrow-band spectra using x-ray reflection in glass capillary optics which have been reported recently in connection with the focusing and generation of parallel x-ray beams. Derivation of formulas for double and triple reflection with and without additional K-edge filtration imply that these methods are superior to the use of filtration alone. It is shown that the double reflection scheme is most sensitive to the angular divergence of the beam emanating from the capillary array used to generate the incident parallel beam. Simulations using three reflections predict output spectra which are relatively insensitive to blurring due to angular divergence. A small amount of K-edge filtration in combination with three reflections provides considerable sharpening of the x-ray spectrum. Aside from the spectral selectivity provided by the capillary array, the reduced divergence of the primary transmission may have advantages for scatter rejection in situations where the air gap between the patient and detector is increased by an amount consistent with the resolution requirements of the application. In parallel beam situations, the use of capillary arrays between the patient and detector may also be useful for the rejection of divergent scattered radiation.  相似文献   
997.
Eighty-nine consecutive Chinese patients (69 males, 20 females) with acute myocardial infarction treated by 100 mg recombinant tissue-plasminogen activator (rt-PA) (7 intracoronarily, 82 intravenously) at 3.7 +/- 1.0 hours after onset, and intravenous heparin or dipyridamole therapy started at 3 hours, were studied prospectively. Their mean age was 59.6 +/- 10.6 years. Forty-six patients (51.7%) had anterior and 39 patients (43.8%) had inferior infarcts. Clinical evidence of reperfusion was seen in 63 patients (72.8%), while new complications included hypotension (5.6%), heart failure (6.7%), cardiac arrhythmias (76.4%), hematoma around vascular access sites (23.6%), melena (2.2%) and cerebral infarction (2.2%). Maximal changes in coagulation profiles were seen at 3 hours, including a decrease in fibrinogen (by 64.2%), an increase in FDP by 11.7 times and D-dimers by 4.4 times. Nine patients (10.1%) had recurrence of angina and 6 patients (6.9%) died due to pump failure (5) and reinfarction (1). Angiogram at 14 days confirmed TIMI (2 or 3) patency of infarct related arteries in 62/81 (76.5%) patients, with a mean global ejection fraction of 52.5 +/- 12.4%. Nearly all survivors could maintain class I-II functional status after discharge. The safety and promises of rt-PA for acute myocardial infarction in the Chinese were confirmed.
  相似文献   
998.
999.
1000.
MICs of temocillin, carbenicillin, ticarcillin, mezlocillin, piperacillin and ampicillin were determined for mutant series of Enterobacter cloacae, Citrobacter freundii, Proteus vulgaris, Morganella morganii and Serratia marcescens with inducible, stably derepressed or basal expression of chromosomal Class I beta-lactamases. Ampicillin was inactive (MIC greater than 256 mg/l) both against beta-lactamase-inducible organisms (except C. freundii) and their stably derepressed mutants, whereas basal mutants were sensitive (MIC 2-8 mg/l). Carbenicillin, ticarcillin, mezlocillin, piperacillin (and ampicillin for C. freundii) were active against both inducible and basal organisms (MIC less than 16 mg/l), but inactive against the derepressed mutants (MICs usually greater than 64 mg/l). Temocillin inhibited all the organisms, including the stably derepressed mutants, at 16 mg/l. Derepressed S. marcescens, M. morganii and Pr. vulgaris were as susceptible as the inducible strains and basal mutants. MICs of temocillin for derepressed mutants of E. cloacae and C. freundii were 4-16 fold above those for their inducible parent strains, but remained within the clinical range.  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