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   240485篇
  免费   48849篇
  国内免费   1286篇
耳鼻咽喉   3749篇
儿科学   7187篇
妇产科学   4335篇
基础医学   39660篇
口腔科学   8193篇
临床医学   27620篇
内科学   53198篇
皮肤病学   11537篇
神经病学   25257篇
特种医学   10540篇
外科学   35798篇
综合类   2246篇
现状与发展   5篇
一般理论   103篇
预防医学   13988篇
眼科学   5785篇
药学   19223篇
  40篇
中国医学   2465篇
肿瘤学   19691篇
  2024年   408篇
  2023年   1224篇
  2022年   2950篇
  2021年   6464篇
  2020年   8128篇
  2019年   13729篇
  2018年   13985篇
  2017年   13945篇
  2016年   15495篇
  2015年   16901篇
  2014年   18198篇
  2013年   20178篇
  2012年   16971篇
  2011年   16500篇
  2010年   15776篇
  2009年   11221篇
  2008年   11483篇
  2007年   10279篇
  2006年   9535篇
  2005年   8880篇
  2004年   7965篇
  2003年   7013篇
  2002年   6266篇
  2001年   5278篇
  2000年   4823篇
  1999年   3626篇
  1998年   1390篇
  1997年   1048篇
  1996年   1007篇
  1995年   909篇
  1994年   792篇
  1993年   681篇
  1992年   1670篇
  1991年   1662篇
  1990年   1432篇
  1989年   1299篇
  1988年   1222篇
  1987年   1121篇
  1986年   1073篇
  1985年   933篇
  1984年   681篇
  1983年   597篇
  1982年   426篇
  1981年   397篇
  1980年   352篇
  1979年   539篇
  1978年   441篇
  1977年   395篇
  1976年   353篇
  1974年   370篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
92.
Though distressing and potentially dangerous, sleep apnea may be an under-recognized disease in many countries. The obstructive type, which usually presents with loud snoring and excessive daytime sleepiness, is by far the commonest form. It causes a great deal of medical, social and psychological morbidity as well as an increased mortality. Doctors of different specialties have an important role in detecting and referring suspected patients for early assessment and treatment. Multidisciplinary management in a general hospital and accurate assessment with polysomnography are essential as modern and sometimes effective methods of treatment are becoming available.  相似文献   
93.
94.
95.
96.
97.
The effect of acute and subchronic dosing with etodolac on the renal PGE2 and 6-keto-PGF concentrations in the normal rat were studied. Etodolac and other nonsteroidal antiinflammatory drugs (NSAIDs) were administered orally, at equieffective antiinflammatory doses, to normal rats either as a single dose or as seven daily doses. Whole kidney prostaglandin (PG) concentrations were measured. In the acute study, etodolac (3 mg/kg) did not significantly lower the PGE2 levels for up to 4 hr postdosing. In contrast, naproxen (3 mg/kg) and piroxicam (0.5 mg/kg) significantly decreased the PGE2 levels to about 20% and 60% of control, respectively. Similar reductions in 6-keto-PGF concentrations were observed. In the subchronic study, etodolac (3 mg/kg/day) did not lower either PGF2 or 6-keto-PGF concentrations whereas naproxen (3 mg/kg/day), piroxicam (0.5 mg/kg/day), indomethacin (1 mg/kg/day), and aspirin (300 mg/kg/day) significantlydecreased both PGs. In both studies, the effect of etodolac was significantly different from that of the NSAIDs. It is concluded that etodolac possesses only a very weak capacity to lower renal PGs, and therefore is unlikely to cause any renal complications related to PG biosynthesis inhibition.  相似文献   
98.
OBJECTIVE: The aim of this study was to evaluate the usefulness of measurement of the angle between bilateral renal pelves on axial views in the prenatal ultrasonographic diagnosis of horseshoe kidney. METHODS: We retrospectively measured the renal pelvic angle in 19 fetuses with horseshoe and 20 fetuses with normal kidneys in the second and third trimesters. Renal pelvic angle was defined as the angle between the long axis of the renal pelves on the axial view of the abdomen. We compared the renal pelvic angles of horseshoe and normal kidneys with unpaired t-test. Taking 140 degrees as a cut-off value, we calculated the sensitivity, specificity and accuracy of pelvic angle measurement for the prenatal diagnosis of horseshoe kidney. RESULTS: The mean pelvic angles in the fetuses with horseshoe kidney were 116 degrees and 110 degrees in the second and third trimester, respectively. In the normal fetuses, the equivalent angles were 172 degrees and 161 degrees. The difference between the two groups was statistically significant (P < 0.01). Using 140 degrees as the discriminating criterion, the sensitivity, specificity and accuracy of renal pelvic angle measurement for the prenatal diagnosis of horseshoe kidney were all 100%. Fifteen of 19 fetuses with horseshoe kidney had no other abnormality. Four (21%) fetuses had severe complex abnormalities which were associated with trisomy 18 in three cases. CONCLUSION: Observation and measurement of the renal pelvic angle is a simple and useful method in the prenatal diagnosis of the horseshoe kidney.  相似文献   
99.
Serum IgA and IgG functional antibodies and their subclasses to Streptococcus pneumoniae capsular antigen found in two aged‐matched cohorts of children with and without otitis media with effusion The relationship between acute otitis media and otitis media with effusion (OME) is uncertain and the aetiology of OME is multifactorial. Otitis media with effusion may be an inflammatory condition; both bacteria and viral infections could play a part in this inflammation. The four bacteria Streptococcus pneumoniae, Haemophilus influenza, Staphylococcus aureus and Branhamella catarrhalis cause 60% of the infections whereas S. pneumoniae accounts for up to 35%. IgA provides the dominant surface response to polysaccharide and lipopolysaccharide antigens, of which IgA2 is the main subclass. Once the mucosa has been breached, most protection is provided by IgG. IgG2 acts mainly against bacterial capsular antigens. This study looked at two groups of 50 children with and without OME who were aged between 3 and 10 years. The aims were to determine if, firstly, the levels of the serum immunoglobulins were different in the two groups, secondly whether these children made the appropriate antibody response to the capsular antigen to S. pneumoniae (PCP), and finally if there was a delay in the maturity of the IgA response. The total IgG, IgA and all subclass levels were measured using radial immunodiffusion. Levels of functional IgA and IgG were measured using ELISAs (25 patients in each group). The results were analysed with non‐parametric tests. The immunoglobulin levels were within the normal levels for both groups. There were very good correlations between the IgG total anti‐PCP and the IgG2 anti‐PCP (R > 0.9, p = 0.001). There was a good correlation between the levels of both IgG total and IgG2 anti‐PCP against IgA total anti‐PCP in both groups (R > 0.85, p > 0.01). This confirms a normal antibody response between both groups of patients. The ages of the controls and patients (50 samples) were correlated with increasing titres of circulating functional antibodies (P = 0.001). This is highly suggestive of a normal age‐related response. In conclusion, the findings were contradictory to our original hypothesis that there is a subtle difference in surface protection between children with and without OME. We believe that a previous history of recurrent acute otitis media is unrelated to the development of OME after 3 years of age.  相似文献   
100.
This study examined the effects of cognitive-behavioral group therapy (CBT) on the self-esteem, depression, and self-efficacy of runaway adolescents residing in a shelter in Seoul, South Korea. The study used a control group pretest-posttest design. The experimental group and the control group consisted of 14 and 13 male subjects, respectively, with subjects having been randomly assigned to these groups. The experimental group participated in a CBT that consisted of eight sessions over an 8-week period; the control group did not participate in the program. To examine the effects of the CBT on dependent variables, the Wilcoxon signed rank test was used. The scores on depression decreased significantly (z = -2.325, p = .02) and those on self-efficacy increased significantly (z = -2.098, p = .03) after the intervention in the experimental group. There was no significant change on self-esteem (z = -1.19, p = .23). In the control group, the scores on depression, self-esteem, and self-efficacy did not change significantly after the intervention period. The CBT developed in this study consisted of structured and specific content that could be usefully applied to runaway adolescents residing in a shelter.  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