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   1338602篇
  免费   96150篇
  国内免费   2957篇
耳鼻咽喉   19759篇
儿科学   40300篇
妇产科学   38722篇
基础医学   187713篇
口腔科学   39864篇
临床医学   112924篇
内科学   263643篇
皮肤病学   30244篇
神经病学   106673篇
特种医学   53830篇
外国民族医学   435篇
外科学   209041篇
综合类   31058篇
现状与发展   6篇
一般理论   438篇
预防医学   92123篇
眼科学   31420篇
药学   100436篇
  4篇
中国医学   2997篇
肿瘤学   76079篇
  2018年   11815篇
  2015年   11962篇
  2014年   16823篇
  2013年   25371篇
  2012年   33206篇
  2011年   35108篇
  2010年   20864篇
  2009年   20361篇
  2008年   33817篇
  2007年   36916篇
  2006年   37477篇
  2005年   36238篇
  2004年   35292篇
  2003年   34283篇
  2002年   33800篇
  2001年   63734篇
  2000年   65446篇
  1999年   55514篇
  1998年   14699篇
  1997年   13492篇
  1996年   12963篇
  1995年   12249篇
  1994年   11498篇
  1992年   42843篇
  1991年   41359篇
  1990年   40640篇
  1989年   39640篇
  1988年   37024篇
  1987年   36488篇
  1986年   34962篇
  1985年   33170篇
  1984年   24870篇
  1983年   21081篇
  1982年   12682篇
  1981年   11578篇
  1980年   10783篇
  1979年   23943篇
  1978年   17091篇
  1977年   14845篇
  1976年   13395篇
  1975年   15283篇
  1974年   18099篇
  1973年   17575篇
  1972年   16835篇
  1971年   15736篇
  1970年   14926篇
  1969年   14359篇
  1968年   13475篇
  1967年   12021篇
  1966年   11262篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
941.
Designed to help persons with schizophrenia to persist and perform better at job placements, the Indianapolis Vocational Intervention Program (IVIP) is a program of cognitive-behavioral group and individual interventions. While its feasibility has been previously demonstrated, it is unknown whether IVIP assists persons to achieve greater levels of participation in vocational rehabilitation and higher levels of job performance. In this study, 100 participants with schizophrenia or schizoaffective disorder were offered a six month job placement and randomized to receive IVIP (n = 50) or support services (n = 50) matched for treatment intensity. Number of hours worked was recorded weekly and job performance was assessed biweekly using the Work Behavior Inventory with raters blind to condition. t-tests revealed that participants in the IVIP group worked a significantly greater number of weeks than those in the support condition. Also, repeated measures ANOVA revealed the IVIP group worked more hours across that 26 week period as well. And with regards to work performance, repeated measures of the 56 participants who worked for at least two-thirds of the intervention revealed that participants in the IVIP group had generally better work performance than those in the support condition. Results suggest a connection between cognitive-behavioral interventions and higher levels of work performance in people with schizophrenia.  相似文献   
942.
943.
Background: In elderly patients, opioids may cause prominent postoperative sedation and respiratory depression. We evaluated the influence of age on the effects of opioids and plasma concentrations of fentanyl and oxycodone in cardiac surgery patients.
Methods: Thirty (≥75 years, gender M9/F21) and 20 (≤60 years, gender M20/F0) patients scheduled to undergo cardiac surgery. A standard anesthesia with fentanyl as an opioid was used. Fentanyl plasma concentrations were measured at the end of surgery and 2 h later. After tracheal extubation, when the pain intensity was at least moderate, blood samples for fentanyl and oxycodone plasma concentration measurements were taken. Thereafter, oxycodone hydrochloride 0.05 mg/kg i.v. was administered. After 15 and 45 min, pain intensity, sedation and oxycodone plasma concentration were determined. This test protocol was repeated twice.
Results: The elderly had a higher plasma concentration of fentanyl at the end of surgery than younger patients (5.7±2.2 vs. 3.8±1.2 ng/ml, P =0.001). The plasma concentrations of oxycodone were comparable between the groups. The interval between the second and the third oxycodone dose was longer in the elderly patients ( P =0.036). Pain intensity on the verbal rating scale was lower at the 45-min assessment point after all three oxycodone test doses ( P =0.008) and sedation scores were significantly higher after the third dose in the elderly patients ( P =0.035).
Conclusions: In elderly patients, the plasma concentration of fentanyl was higher but plasma levels of oxycodone were at a similar level compared with middle-aged patients. However, the elderly patients had less pain and were more sedated after doses of oxycodone.  相似文献   
944.
945.
946.
947.
948.
949.
PTH has diverse effects on bone metabolism: anabolic when given intermittently, catabolic when given continuously. The cellular mechanisms underlying the varying target cell response are not clear yet. PTH induces RGS-2, a member of the Regulator of G-protein Signaling protein family, via cAMP/PKA, and inactivates PKC-mediated signaling. To investigate intracellular signaling pathways with different PTH concentration-time patterns, we treated UMR 106-01 osteoblast-like cells in a perfusion system. PTH was administered intermittently (4 min/h, 10−7 M) or continuously at an equivalent cumulative dose (6.6 × 10−9 M). cAMP was measured using radioimmunoassay, mRNA levels using real-time rtPCR and ribonuclease protection assay, and protein levels using Western immunoblotting. A single PTH pulse transiently increased cAMP levels by 2000% ± 1200%. In contrast to continuous PTH exposure, cAMP induction remained unchanged with intermittent PTH, ruling out desensitization of the PTH receptor. In continuously perfused cells, RGS-2 abundance was three to five times higher than in cells intermittently exposed to PTH for up to 12 h. MKP-1 and -3 were significantly less induced with pulsatile PTH; exposure-mode-dependent differences in MMP-13 and IGFBP-5 were small. Pulsatile but not continuous PTH administration prevents PTHrP receptor desensitization and accumulation of RGS-2 in osteoblasts, which should preserve PKC-dependent signaling.  相似文献   
950.
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