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   4429篇
  免费   282篇
  国内免费   17篇
耳鼻咽喉   30篇
儿科学   170篇
妇产科学   94篇
基础医学   720篇
口腔科学   62篇
临床医学   294篇
内科学   744篇
皮肤病学   150篇
神经病学   319篇
特种医学   79篇
外科学   463篇
综合类   117篇
一般理论   5篇
预防医学   341篇
眼科学   147篇
药学   520篇
中国医学   72篇
肿瘤学   401篇
  2023年   24篇
  2022年   54篇
  2021年   98篇
  2020年   78篇
  2019年   97篇
  2018年   125篇
  2017年   79篇
  2016年   102篇
  2015年   126篇
  2014年   159篇
  2013年   247篇
  2012年   324篇
  2011年   333篇
  2010年   206篇
  2009年   144篇
  2008年   239篇
  2007年   217篇
  2006年   256篇
  2005年   206篇
  2004年   177篇
  2003年   154篇
  2002年   169篇
  2001年   110篇
  2000年   105篇
  1999年   65篇
  1998年   43篇
  1997年   34篇
  1996年   19篇
  1995年   19篇
  1994年   17篇
  1993年   17篇
  1992年   53篇
  1991年   53篇
  1990年   42篇
  1989年   55篇
  1988年   37篇
  1987年   31篇
  1986年   26篇
  1985年   35篇
  1984年   26篇
  1983年   30篇
  1982年   14篇
  1981年   14篇
  1980年   17篇
  1979年   31篇
  1978年   17篇
  1977年   21篇
  1974年   16篇
  1972年   15篇
  1970年   13篇
排序方式: 共有4728条查询结果,搜索用时 750 毫秒
101.
It is well established that the immune potential declines with age. However, there is a great paucity of information regarding role of monocytes in elderly suffering from cerebrovascular accident. This present study was undertaken to investigate if the functions of peripheral blood mononuclear cells have any correlation to the manifestation of an age-associated cerebrovascular disorders: myocardial infraction, cerebrovascular (infract & hemorrhage). An age-associated inhibition in the production of interleukin-1 (IL-1) by monocytes was observed while the production of nitric oxide (NO) remained unaltered in the response of monocytes, obtained from normal elderly donors, to Lipopolysaccharide (LPS) treatment in vitro. Cerebrovascular pathologies were found to be associated with an augmentation of IL-1 production by monocyte, while NO production was augmented in case of CVA (hemorrhage) and MI. Trace element copper was found to be lower in the serum of patients suffering from CVA, while concentration of zinc was found to be elevated in serum compared to these trace elements in normal adults. Thus these factors are likely to play a role in the pathogenesis of age-related cerebrovascular disorders.  相似文献   
102.
Introduction: Quadriceps angle (Q angle) is one of the most important indicators of stability of patello-femoral joint. Orthopedic surgeons often measure the Q angle clinically in patients suffering from patello-femoral joint dysfunction or in subjects particularly young active sportspersons who are prone to injury of this joint. But the clinical method of measurement of Q angle is not standardized, and its value depends on various methods used. But the radiological method of measurement of Q angle is more accurate. However, due to the expense and time involved, the clinical method is preferred over the radiological one in practice. Aim: This study was aimed at studying the correlation and regression between the radiographic Q-angle values and the clinical ones, so that the former can be predicted easily from the latter. Materials and methods: Q angle was measured both clinically and radiographically in both knee joints of 93 adult subjects in North Bengal Medical College and Hospital. Result: Statistically significant correlation followed by the regression analysis could reveal simple linear regression equations for predicting the radiological Q-angle values from the clinical Q angle, derived separately in both males and females in right and left sides, separately. Conclusion: Thus, from a known clinical Q-angle value, we can derive the respective radiological Q angle, indirectly avoiding the entire troublesome maneuver in regular practice. So the present study recommends this method in clinical fields because this is a more rational and ideal approach to estimate the radiological Q angle. Increase in the Q angle beyond 20–22° predisposes to patellar dislocation which should be kept in mind while screening athletes, especially females. This tendency can be countered by quadriceps exercises and appropriate footwear.  相似文献   
103.
Objective:Comparing the efficacy, safety and outcome of percutaneous intrervention for Budd-Chiari Syndrome (BCS) patients with bilirubin less than 3 and 3–6 mg dl−1.Methods and materials:188 BCS patients having serum bilirubin ≤6 mg dl−1 and underwent percutaneous interventions were divided into two groups based on bilirubin level: 151 patients having bilirubin <3 mg dl−1 were included in Group 1; and 37 patients having bilirubin 3–6 mg dl−1 were included in Group 2. Both group were compare for technical success (successful recanalization of hepatic venous stenosis or creation of portocaval shunt with post-procedure gradient ≤5 mm of Hg), Safety (procedure-related mortality/morbidity or patient required transplantation) and outcome (resolution of clinical symptoms and survival).Results:Technical success was 94.7% in Group 1–89.1% in Group 2 with overall success rate was 93.6%. No significant differences observed between the two groups in regards to procedure related complication. Overall transplant-free survival at 1 and 5 years after intervention in both groups was 96.3 and 91.2% respectively. 1-year and 5-year survivals in Group 1 was 96.7%, and 93.1%, whereas Group 2 was 94.6 and 90.1% with no statically significantly difference between the two groups (p = 0.59). Percutaneous intervention results are good in patients having bilirubin up to 6 mg dl−1, i.e. mild to moderate liver dysfunctions.Conclusion:Technical success, survival and outcome of percutaneous intervention in BCS patients having serum bilirubin 3–6 mg dl−1 was comparable to patients having bilirubin level <3 mg dl−1.Advances in knowledge:Percutaneous intervention treatment is suitable for treatment for symptomatic BCS patients having bilirubin up to 6 mg  dl−1.  相似文献   
104.
105.
External influence is essential for any change to occur in this world. Similarly, the reaction path of a chemical reaction can be changed with the addition of a catalyst from outside. Sometimes a catalyst performs better when it remains associated with an inert substance, which is called a support material (SM). Improved catalyst accomplishment arises from the ‘proximity effect’. Even inert supports play a role in better product formulation or environmental remediation. In this review, it has been shown how the SM, as a nest, aids the catalyst particle synergistically to perform a good job in a chemical reaction. The structure–function relationship of SM helps in catalyst activation to some extent, and produces active centres that are difficult to fully ascertain. In the text, Langmuir–Hinshelwood (L–H), Mars-van Krevelen (MVK), and Eley–Rideal (E–R) mechanisms are highlighted for the adsorption processes as the case may be. Again, the importance of SM for both catalyst and substrates has been consolidated here in the text. Finally, the role of the initiator and the promoter is also discussed in this review.

Catalysts are empowered with proper support materials (SM). The proximity effect, in other word ‘synergism’ between the two, is still necessary to be explored at the molecular level to revamp this never ending field of catalysis.  相似文献   
106.
107.
108.
Background:Functional brace application for isolated humeral shaft fracture persistently yields good results. Nonunion though uncommon involves usually the proximal third shaft fractures. Instead of polyethylene bivalve functional brace four plaster sleeves wrapped and molded with little more proximal extension expected to prevent nonunion of proximal third fractures. Periodic compressibility of the cast is likely to yield a better result. This can be applied on the 1st day of the presentation as an outpatient basis. Comprehensive objective scoring system befitting for fracture humeral shaft is a need.Results:The results were assessed using 100 point scoring system where union allotted 30 points and 60 points allotted for angulations (10), elbow motion (10), shoulder abduction (10), shortening (5), rotation (5), absence of infection (10), absence of nerve palsy during treatment (10). Remaining 10 points were allotted for five items with two points each. They were the absence of skin sore, absence of vascular problem, absence of reflex sympathetic dystrophy (RSD), recovery of paralyzed nerve during injury and recovery of paralyzed nerve during treatment. Results were considered excellent with 90 and above, good with 80–89, fair with 70–79 and poor below 70 point. Results at 6 months were excellent in 43.94% (n = 29), good in 42.42% (n = 28), fair in 9.1% (n = 6), poor in 4.55% (n = 3). Union took place in 98.48% (n = 65) with an average of 10.3 weeks (range 6–16 weeks). 87.5% (n = 7) paralyzed radial nerve recovered. All wounds healed. Four patients had transient skin problem. One patient with mid shaft fracture had nonunion due to the muscle interposition.Conclusion:Modified functional cast brace is one of the options in treatment for humeral shaft fractures as it can be applied on the 1st day of the presentation in most of the situations. Simple objective scoring system was useful particularly in uneducated patients.  相似文献   
109.
110.
The synthesis and processing of structural proteins of human immunodeficiency virus type 1 (HIV-1) were studied in infected cells treated with monensin and cerulenin. In MOLT-3 cells chronically infected with HTLV-IIIB, monensin inhibited the proteolytic cleavage of the env-coded polyprotein gp160 to gp120, leading to the accumulation of the precursor gp160. The formation of syncytia normally observed when CEM cells are cocultivated with HIV-1-infected MOLT-3 cells was significantly inhibited in the presence of monensin. The effect of the ionophore on the culture was reversible, as withdrawal of monensin from the medium restored the ability of the cells to form syncytia with CEM cells and led to the resumption of the processing of gp160 to gp120. Monensin did not affect the synthesis and processing of gag-coded proteins and regulatory proteins. Cerulenin, an inhibitor of de novo fatty acid biosynthesis, inhibited the myristoylation and the proteolytic cleavage of the gag-coded polyprotein Pr53gag to p24 but did not affect the processing of gp160. However, use for monensin and cerulenin as antiviral agents for treatment of HIV-1 infection cannot be foreseen because of the pronounced in vitro toxicity observed.  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