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   5123篇
  免费   280篇
  国内免费   10篇
耳鼻咽喉   31篇
儿科学   363篇
妇产科学   81篇
基础医学   441篇
口腔科学   180篇
临床医学   323篇
内科学   1136篇
皮肤病学   268篇
神经病学   294篇
特种医学   124篇
外科学   743篇
综合类   186篇
预防医学   245篇
眼科学   308篇
药学   438篇
中国医学   13篇
肿瘤学   239篇
  2023年   38篇
  2022年   76篇
  2021年   170篇
  2020年   75篇
  2019年   152篇
  2018年   191篇
  2017年   131篇
  2016年   158篇
  2015年   166篇
  2014年   214篇
  2013年   224篇
  2012年   387篇
  2011年   448篇
  2010年   234篇
  2009年   177篇
  2008年   247篇
  2007年   284篇
  2006年   207篇
  2005年   196篇
  2004年   170篇
  2003年   142篇
  2002年   159篇
  2001年   109篇
  2000年   114篇
  1999年   90篇
  1998年   41篇
  1997年   19篇
  1996年   20篇
  1995年   35篇
  1994年   17篇
  1992年   69篇
  1991年   64篇
  1990年   41篇
  1989年   37篇
  1988年   53篇
  1987年   39篇
  1986年   32篇
  1985年   38篇
  1984年   27篇
  1983年   23篇
  1979年   22篇
  1977年   15篇
  1975年   16篇
  1974年   26篇
  1973年   15篇
  1972年   27篇
  1971年   19篇
  1970年   15篇
  1969年   16篇
  1968年   18篇
排序方式: 共有5413条查询结果,搜索用时 31 毫秒
91.
92.
93.
Background: Conventional oral dosage forms exhibit poor/low bioavailability due to incomplete release of drug and short residence time at the absorption site. Gastro-retentive drug delivery system (GRDDS) is particularly used to improve bioavailability of the drugs, which have narrow absorption window down in the levels of gastrointestinal tract and also to treat local disorders.

Purpose: The purpose of this review is to describe the utility of the nanofibers as gastro-retentive dosage form. From last few decades, formulation scientists have put extensive efforts to develop suitable gastro-retentive drug delivery system, which is appropriate for commercialization. Current approaches used for preparation of gastro-retentive drug delivery system offers limited functional features to control the floating behavior. Recently, an extensive research has been developed to improve the gastric residence time by using nanofibers, which ultimately leads to the increased bioavailability of the drug. Multiple functional features and unique properties of nanofibers improve its gastro retention.

Conclusion: Nanofiber system provides stomach-specific drug release for longer duration; moreover, increased local action of the drug due to prolonged contact time with the gastric mucosa. Thus, the nanofiber system promises to be the potential approach for gastric retention drug delivery system.  相似文献   
94.
95.
Metabolic Brain Disease - Patients with liver disease often have alteration of neurological status which requires admission to an intensive care unit. Patients with acute liver failure (ALF),...  相似文献   
96.
This study compared external insulin pump treatment using insulin lispro or insulin aspart with multiple daily injections (MDI; four or more injections per day) using insulin glargine and insulin lispro or insulin aspart. An electronic database was used to retrieve various parameters of glycemic control for 515 adult patients with type 1 diabetes. An insulin pump was used by 216 patients, and 299 patients were taking insulin glargine for at least 6 months. The mean age (approximately 33 years), duration of diabetes (approximately 16 years), and duration of treatment (approximately 12 months) were similar for both the pump and insulin glargine groups. The mean (+/-SEM) A1C values were significantly reduced in both groups from the baseline to the end of the study (7.7 +/- 0.1% to 7.5 +/- 0.1% for the pump group and 8.0 +/- 0.1% to 7.7 +/- 0.1% for the insulin glargine group, P< 0.001) with similar weight gain (P> 0.05) in both groups. The insulin glargine group significantly reduced basal insulin intake at follow-up. The premeal boluses were similar throughout the study for both groups. The subjects reporting severe hypoglycemic episodes were similar in the two groups; however, there were 12 cases of diabetic ketoacidosis reported in the pump group and none in the insulin glargine group. Patients with type 1 diabetes can achieve similar glycemic control using insulin glargine with premeal insulin lispro or by using an external infusion pump with insulin lispro or insulin aspart. However, costs and episodes of diabetic ketoacidosis are significantly higher for insulin pump users.  相似文献   
97.
M Garg  C D Lew  A D Ramos  A C Platzker  T G Keens 《Chest》1991,100(3):770-774
Extracorporeal membrane oxygenation (ECMO) is a highly invasive therapy for intractable neonatal respiratory failure, and serious complications may occur with increasing duration of bypass. Weaning from bypass is empirical at present. Thus, there is a need to accurately predict when infants can be successfully decannulated. We hypothesized that pulmonary mechanics would reflect lung recovery and, therefore, predict successful weaning from ECMO. We measured pulmonary mechanics daily in 22 neonates, at gestational age of 37.8 +/- 0.6 weeks (SE) requiring ECMO for severe respiratory failure (oxygen index 66 +/- 6). Pulmonary resistance (Rpul), dynamic compliance (Cdyn), and tidal volume (VT) were measured. Rpul did not predict lung recovery. Cdyn within 24 hours of starting ECMO was 0.3 +/- 0.04 ml/cm H2O. Cdyn within 24 hours of weaning from ECMO was 1.2 +/- 0.09 ml/cm H2O (p less than 0.001). All 22 infants had Cdyn greater than 0.6 ml/cm H2O at the time of decannulation, but four infants (20 percent) with Cdyn less than 0.6 ml/cm H2O could not be weaned from ECMO within 20 hours (p less than 0.01). Thus, a minimum Cdyn of 0.6 ml/cm H2O is associated with successful weaning from ECMO. Cdyn of 0.8 ml/cm H2O provided better overall discrimination between those who could be successfully weaned from ECMO. We conclude that serial measurement of dynamic pulmonary compliance predicts successful weaning from ECMO.  相似文献   
98.
There is limited data on the efficacy of paclitaxel-coated balloon (PCB) compared to stents for de novo coronary lesions. The purpose of this study was to compare the efficacy of PCB treatment with stent implantation for de novo coronary lesions after successful plain old balloon angioplasty (POBA) guided by fractional flow reserve (FFR). In 200 patients scheduled for elective percutaneous coronary intervention (PCI) for de novo lesions, FFR was measured after POBA (POBA–FFR). If POBA–FFR was ≥?0.75, patients were treated with PCB (PCB group, n?=?78) or stent (Stent group, n?=?73). If POBA–FFR was <?0.75, stent was implanted as planned (Reference group, n?=?42). The primary endpoint was late lumen loss at 9 months and the secondary endpoint was adverse cardiac events (cardiac death, myocardial infarction, target lesion thrombosis, or repeat revascularization) at 12 months follow-up. There was no between-group differences in the POBA–FFR (0.87?±?0.05 in PCB, 0.89?±?0.06 in stent, p?=?0.101). At 9 months, late lumen loss was significantly lower in the PCB group compared to the Stent group (0.05?±?0.33 vs. 0.59?±?0.76 mm, p?<?0.001). Adverse cardiac events were not different between the PCB, Stent and Reference groups (2.6, 5.5, and 9.5% respectively; p?=?0.430 for PCB vs. Stent group; p?=?0.229 for the reference vs. both other groups). PCB treatment guided by POBA–FFR showed excellent 9 months angiographic and functional results, as well as comparable 12 months clinical outcomes, compared with stent implantation for de novo coronary lesions.  相似文献   
99.

Objective

To ascertain whether temporal and geographic interest in seeking cardiovascular disease (CVD) information online follows seasonal and geographic patterns similar to those observed in real-world data.

Methods

We searched Google Trends for popular search terms relating to CVD. Relative search volumes (RSVs) were obtained for the period January 4, 2004, to April 19, 2014, for the United States and Australia. We compared average RSVs by month and season and used cosinor analysis to test for seasonal variation in RSVs. We also assessed correlations between state-level RSVs and CVD burden using an ecological correlational design.

Results

RSVs were 15% higher in the United States and 45% higher in Australia for winter compared with summer (P<.001 for difference for both). In the United States, RSVs were 36% higher in February compared with August, while in Australia, RSVs were 75% higher in August compared with January. On cosinor analysis, we found a significant seasonal variability in RSVs, with winter peaks and summer troughs for both the United States and Australia (P<.001 for zero amplitude test for both). We found a significant correlation between state-level RSVs and mortality from CVD (r=0.62; P<.001), heart disease (r=0.58; P<.001), coronary heart disease (r=0.48; P<.001), heart failure (r=0.51; P<.001), and stroke (r=0.60; P<.001).

Conclusion

Google search query volumes related to CVD follow strong seasonal patterns with winter peaks and summer troughs. There is moderate to strong positive correlation between state-level search query volumes and burden of CVD mortality.  相似文献   
100.
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