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   3670篇
  免费   218篇
  国内免费   26篇
耳鼻咽喉   32篇
儿科学   43篇
妇产科学   25篇
基础医学   439篇
口腔科学   103篇
临床医学   162篇
内科学   953篇
皮肤病学   109篇
神经病学   340篇
特种医学   103篇
外科学   668篇
综合类   12篇
预防医学   245篇
眼科学   96篇
药学   190篇
中国医学   9篇
肿瘤学   385篇
  2023年   23篇
  2022年   24篇
  2021年   70篇
  2020年   36篇
  2019年   50篇
  2018年   73篇
  2017年   67篇
  2016年   81篇
  2015年   81篇
  2014年   109篇
  2013年   141篇
  2012年   211篇
  2011年   262篇
  2010年   145篇
  2009年   120篇
  2008年   194篇
  2007年   220篇
  2006年   177篇
  2005年   244篇
  2004年   207篇
  2003年   199篇
  2002年   214篇
  2001年   75篇
  2000年   81篇
  1999年   75篇
  1998年   40篇
  1997年   46篇
  1996年   30篇
  1995年   26篇
  1994年   34篇
  1993年   30篇
  1992年   72篇
  1991年   50篇
  1990年   36篇
  1989年   39篇
  1988年   39篇
  1987年   47篇
  1986年   33篇
  1985年   27篇
  1984年   18篇
  1983年   20篇
  1982年   11篇
  1979年   16篇
  1978年   9篇
  1975年   10篇
  1974年   10篇
  1973年   12篇
  1971年   11篇
  1969年   13篇
  1967年   10篇
排序方式: 共有3914条查询结果,搜索用时 15 毫秒
51.
A survey was conducted in the second half of a work week on 39 male workers who were occupationally exposed to styrene in combination with methanol and methyl acetate during the production of plastic buttons. Time-weighted average exposure during an 8-h shift to styrene (Sty-A) and methyl acetate was monitored by carbon cloth-equipped personal samplers and to methanol by water-equipped ones. Urine samples were collected near the end of the shift and analyzed for mandelic (MA-U) and phenylglyoxylic acids (PhGA-U) by HPLC. Geometric mean styrene concentration was 12.4 ppm (g/g) with the maximum of 46 ppm, whereas the values for methanol and methyl acetate in combination were 23.5 ppm and 229 ppm, respectively. The relationship of MA-U and PhGA-U with Sty-A was examined by linear regression analysis. The equations for the regression lines were compared with the results from a previous survey (Ikeda et al. 1983) in which workers were exposed only to styrene, and the methods employed were identical with that in the present study. The comparison showed no evidence to suggest that styrene metabolism is suppressed by coexposure to methanol and methyl acetate at low concentrations below the current occupational exposure limit of 200 ppm.  相似文献   
52.
The delayed neurotoxic organophosphate, diisopropylfluorophosphate (DFP) binds with high affinity to membrane-bound proteins from chicken nerve tissues. The autoradiographic distribution of [3H]DFP binding sites in spinal cord sections of chicken showed higher concentrations of binding sites in gray matter than in white matter. In the cervical region, fairly high densities of [3H]DFP binding sites were found in laminae X and to a lesser extent, in the ventral horn gray matter. To identify the membrane-associated DFP-binding proteins, detergent-solubilized membranes were labeled widi 5-10nM [3H]DFP (10pmol/mg protein) for 70 min at 37°C. Gel-exclusion chromatography of the [3H]DFP-radiolabeled membranes indicated at least two major radioactive proteins with apparent molecular weights of 150-670 kDa and 40-129 kDa. Although we could not identify the high affinity DFP binding proteins, the autoradiographic experiments clearly demonstrated that the DFP binding proteins localized on gray matter of chicken spinal cord.  相似文献   
53.
Effect of rotational alignment on patellar tracking in total knee arthroplasty   总被引:13,自引:0,他引:13  
Forty-four consecutive patients (65 knees) who underwent identical condylar type total knee arthroplasty were evaluated retrospectively. In 22 of the patients (32 knees), the femoral component was set parallel to the posterior condylar axis (neutrally aligned group). In the remaining 22 patients (33 knees), it was set in an external rotation position of 3 degrees to 5 degrees relative to the axis (externally aligned group). Of the total knee arthroplasties in the neutrally aligned group, 34% required lateral release, compared with only 6% in the externally aligned group; patellar tracking in the externally aligned group was significantly better than that in the neutrally aligned group. Postoperative measurements performed using computed tomography scans showed that the mean angle between the prosthetic posterior condylar axis and the transepicondylar axis was 7.9 degrees in the neutrally aligned group and 3.2 degrees in the externally aligned group. The external rotation setting of the femoral component diminished the need for lateral retinacular release and may decrease the rate of patellofemoral complications that occur after total knee arthroplasty.  相似文献   
54.
Prostate-specific antigen values provide important and unique information about prostate cancer to clinicians. However, there is conflicting information about the prognostic significance of the dynamics of PSA decline and elevation after treatment. To provide further insight into the dynamics of PSA as prognostic factors, we herein studied various PSA values as possible prognostic factors in 93 patients with prostate cancer treated with endocrine therapy. Thirteen (14.0%) had stage B tumors, 20 (21.5%) had stage C tumors, and 60 (64.5%) had stage D tumors. The overall 5-year survival rate was 41.2%. Relapse was observed in 32 (34.4%) patients. The influence of pre- and post-treatment PSA (both absolute and percentage values) on survival was analyzed. Normalization of PSA value was associated with prolonged survival regardless of interval to reach the lowest PSA level. The absolute value of PSA at 3 or 6 months following treatment was a significant discriminator, while the pre-treatment PSA level and percentage values of post-treatment PSA were not. These data show that the PSA nadir and PSA value at 3 or 6 months following treatment provide important prognostic information.  相似文献   
55.
56.
A questionnaire survey was carried out among 1041 students in secondary schools and colleges in Dar-es-Salaam, Tanzania to evaluate the relationship between HIV-risky sexual behaviour and anti-condom bias, as well as with AIDS-related information, knowledge, perceptions and attitudes. Self-reportedly, 54% of students (75% of the boys and 40% of the girls) were sexually active, 39% had a regular sexual partner and 13% had multiple partners in the previous year. The condom use rate was higher than previous reports. However, 30% of sexually active respondents did not always use condoms (Risk-1 behaviour) and 35% of those with multiple partners in the previous year did not always use condoms (Risk-2 behaviour). Multiple logistic regression analyses indicated that 'sex partner hates condom' had association with both Risk-1 behaviour (OR 2.47; 95% CI 1.58-3.85) and Risk-2 behaviour (OR 2.47; 95% CI 1.10-5.48). 'Use of condom prevents HIV infection' also had association with both Risk-1 behaviour (OR 2.09; 95% CI 1.19-3.67) and Risk-2 behaviour (OR 3.73; 95% CI 1.28-11.03). Students engaging in risky behaviour were aware of the risk, even though they failed to change their behaviour. Reasons for the AIDS epidemic among Tanzanian students and the importance of more effective AIDS education are also discussed.  相似文献   
57.
Nocturnal eating/drinking syndrome secondary to neuroleptic-induced restless legs syndrome (RLS) occurred under treatment with low-dose haloperidol in a 51-year-old female schizophrenic patient. Polysomnographic investigation showed a low level of sleep efficacy, periodic leg movements, and a strict relationship between nocturnal eating episodes and non-rapid eye movement sleep. Her nocturnal eating and RLS were completely inhibited by clonazepam treatment. To our knowledge, this is the first published case of nocturnal eating/drinking syndrome secondary to neuroleptic-induced RLS.  相似文献   
58.
Adenohypophyses of human newborns contain characteristic psammoma bodies. Their numbers are maximal within 2 weeks of the neonatal period and diminish thereafter. They are very rare in infant pituitaries, seeming to disappear by shrinkage in that there is a significant direct correlation between their number and size. The bodies were found to contain a high concentration of endogenous peroxidase, thus suggesting that the enzyme may be responsible for their disappearance. A statistical majority of psammoma bodies were located within follicular lumens. By immunohistochemistry, the follicular epithelium surrounding psammoma bodies showed immunoreactivity for various pituitary hormones. Light microscopy demonstrated that adenohypophysial cells surrounding psammoma bodies contain randomly, scattered granules or globules exhibiting peroxidase activity. Extrusion of such granules into follicular lumens may play a role in the genesis of the concretions. The conspicuous lamellar nature of the calcified psammoma bodies suggests that waves of calcium deposition occur during their morphogenesis. Despite histologic similarities, the histochemical characteristics of this type of psammoma body differ from those in other organs as well as from the calcification encountered in prolactin (PRL)-producing pituitary adenomas.  相似文献   
59.
Pregnant rats were given 0%-, 5%-, 10%- and 20% ethyl alcohol in drinking water during the gestation period.We evaluated the brain function of pups born of alcohol-administered dams. Learning ability (Sidman avoidance behavior), the amounts of monoamines (noradrenalin, dopamine, serotonin) and metabolites (3,4-dihydroxyphenyl acetic acid [DOPAC], homovanillic acid [HVA] and 5-hydroxyindole acetic acid [5-HIAA])in whole brain were examined for neurobehavioral and neurochemical effects.There was no effect on Sidman avoidance behavior in 56-day-old offspring, but alterations of the amounts of monoamines and their metabolites were observed even in 66-day-old offspring as a result of the dams' exposure to ethanol during pregnancy.  相似文献   
60.
We held a computer software contest at 38th Congress of the JSA, held in March, 1991. The aim is to encourage the members of the Society to write softwares and to help distribute them, especially as Freewares. We received 25 entries for the contest; two-thirds of these are for computers of NEC PC9801 series and a third are for Macintosh. We received donations 3 million yen worth of instruments and goods for prizes plus some cash, which as prizes were distributed to those who made entries for the contest.Most of these programs have been registered as freewares at various computer networks, including our Ether-Net, one of the common computer network SIGBBSs among Japanese anesthesiologists.(Suwa K, Miyasaka K, Tanaka Y, et al.: Report on the computer software contest at 38th congress of the Japan society of anesthesiology. J Anesth 5: 441–444, 1991)Executive Committee of the Computer Software Contest at 38th Congress of the Japan Society of Anesthesiology  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