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   3187509篇
  免费   253214篇
  国内免费   5463篇
耳鼻咽喉   45467篇
儿科学   100281篇
妇产科学   86377篇
基础医学   458075篇
口腔科学   91961篇
临床医学   295264篇
内科学   617189篇
皮肤病学   66089篇
神经病学   265524篇
特种医学   124753篇
外国民族医学   1104篇
外科学   471720篇
综合类   73746篇
现状与发展   4篇
一般理论   1435篇
预防医学   262190篇
眼科学   75209篇
药学   237666篇
  10篇
中国医学   5753篇
肿瘤学   166369篇
  2018年   32992篇
  2017年   25394篇
  2016年   27970篇
  2015年   31817篇
  2014年   45326篇
  2013年   69210篇
  2012年   93460篇
  2011年   99142篇
  2010年   58142篇
  2009年   55749篇
  2008年   94053篇
  2007年   100325篇
  2006年   100687篇
  2005年   98297篇
  2004年   94530篇
  2003年   91133篇
  2002年   89637篇
  2001年   142980篇
  2000年   147535篇
  1999年   124963篇
  1998年   36542篇
  1997年   33114篇
  1996年   33157篇
  1995年   31718篇
  1994年   29827篇
  1993年   27898篇
  1992年   100965篇
  1991年   98165篇
  1990年   94926篇
  1989年   91573篇
  1988年   85180篇
  1987年   83712篇
  1986年   79590篇
  1985年   75891篇
  1984年   57674篇
  1983年   49804篇
  1982年   30151篇
  1981年   26989篇
  1979年   54638篇
  1978年   38975篇
  1977年   32800篇
  1976年   30699篇
  1975年   32653篇
  1974年   40085篇
  1973年   38541篇
  1972年   36349篇
  1971年   33715篇
  1970年   31718篇
  1969年   29666篇
  1968年   27224篇
排序方式: 共有10000条查询结果,搜索用时 640 毫秒
971.
This study examined the ability of PCR to amplify Leishmania DNA, stored on Giemsa-stained slides, from American cutaneous leishmaniasis (ACL) patients. In total, 475 slides stored for up to 36 years were obtained from an outpatient clinic in a Brazilian ACL-endemic region, and Leishmania DNA was amplified from 395 (83.2%) of the DNA samples using primers specific for the minicircle kinetoplast DNA. Restriction fragment length polymorphism analysis of these amplicons demonstrated that Leishmania (Viannia) braziliensis was the only species present in these samples. The results demonstrated that archived Giemsa-stained slides can provide a Leishmania DNA source for performing clinical and epidemiological studies of leishmaniasis.  相似文献   
972.
A rapid procedure for determining angiotensin II in the blood by inverse voltammetry using a TA-2 device (Tekhnoanalit Company, Tomsk) with a graphite electrode has been developed. The results of analyses using the proposed technique agree with the clinical data. The rapid analytical procedure favors optimization of cardiotropic drug therapy. __________ Translated from Khimiko-Farmatsevticheskii Zhurnal, Vol. 40, No. 12, pp. 54–56, December, 2006.  相似文献   
973.
974.
Decreases in sex hormone levels with menopause may bring about a number of consequences in women's general health and sexual well-being, especially when levels decline suddenly and prematurely, as in surgical menopause. In addition to the well-established role of estrogens in preserving the biological basis of sexual response, there is emerging evidence that androgens are significant independent determinants affecting sexual desire, activity and satisfaction, as well as mood, energy and other components of women's health. Hypoactive sexual desire disorder (HSDD), a persistent absence of sexual fantasies or thoughts and/or desire for and receptivity to sexual activity that causes personal distress, is experienced by some postmenopausal women. Even though conventional hormone therapy with estrogens or estrogens and progestogens may be effective for vaginal atrophy, increasing vaginal lubrication and reducing dyspareunia, it has not been shown to consistently increase sexual desire or activity and many women with sexual dysfunction remain unresponsive. Several recent, large, phase III studies have shown that the addition of transdermal testosterone to conventional hormone therapy can be helpful in surgically menopausal women presenting with HSDD. After 24 weeks of treatment in these studies, testosterone-treated women experienced significantly greater increases in satisfying sexual activity and sexual desire, and greater decreases in distress, than placebo-treated women. Accurate clinical assessment and individualized management of sexual symptoms are fundamentally important for all menopausal women with HSDD or other sexual problems.  相似文献   
975.
We report a case of a prepubertal girl with juvenile primary hypothyroidism presenting as ovarian cysts and precocious puberty. The 7-year-old female was referred to our clinic because of a pelvic/abdominal mass and vaginal bleeding. Besides these findings, on physical examination we noticed the thyroid gland globally increased and the presence of secondary sexual characteristics. Based upon the clinical profile and investigations, the patient was diagnosed with juvenile primary hypothyroidism due to autoimmune thyroiditis. The cysts and precocious puberty resolved spontaneously after the simple replacement of thyroid hormone. It is important to bear in mind hypothyroidism in cases of girls presenting ovarian cysts and precocious puberty in order to avoid unnecessary surgery on the ovaries.  相似文献   
976.
OBJECTIVE: To assess the effects of adding combined estradiol/norethisterone acetate therapy (CENT) to goserelin acetate treatment (GA) of dysfunctional uterine bleeding (DUB) in perimenopausal women. METHODS: In a randomized, placebo-controlled, double-blind trial followed by an open follow-up study, 31 perimenopausal women with DUB were recruited from gynecological outpatient departments of two Dutch hospitals and randomized for treatment with either GA/placebo or GA/CENT for 6 months followed by 18 months of GA/CENT for all. The main outcome measures were abdominal pain, number of bleeding days, double-layer endometrial thickness (DET), Greene climacteric score (GCS), visual analog scale for well-being, bone mineral density (BMD) and mammographic density (BI-RAD score). RESULTS: Abdominal pain, number of bleeding days and DET decreased in both groups, the between-group difference in decrease not being statistically significant. GCS initially showed significant improvement in the GA/CENT group. BMD decreased significantly in the GA/placebo group (-4.1%) compared with the GA/CENT group (-0.3%). Another 18 months of GA/CENT did not result in a lasting difference in BMD between groups. BI-RAD scores did not differ significantly between or within the two groups. CONCLUSIONS: Adding CENT to GA treatment for DUB in perimenopausal women initially prevented BMD loss and improved climacteric complaints, while having no negative impact on vaginal bleeding, abdominal pain or BI-RAD scores. However, prolonged treatment did not result in a lasting prevention of bone loss.  相似文献   
977.
The aim of this study was to assess the incidence and risk factors of pelvic fractures as a result of radiation therapy in women with gynecological cancer. We retrospectively reviewed 3530 female patients treated at our institute between 1980 and 1998 with megavoltage radiation with or without brachytherapy for cancer in the pelvic area. Eligible were patients with vulvar, vaginal, cervical, endometrial, and fallopian tube cancer. Median follow-up was 88 months (range 0-240). Emphasis was put on treatment-related and patient-related risk factors. Of the eligible 3155 patients, 15 developed symptomatic bone fracture caused by osteoradionecrosis, which makes an overall incidence of 0.44% The diagnosis was based on anamnesis, clinical course, and X-ray or computed tomography images. Median time of onset was 44 months (range 6-197). All patients had pain as the first symptom. The only independent predictive factor for developing osteoradionecrosis seemed to be preexistent osteoporosis. Other risk factors that are related to osteoporosis include higher age, postmenopausal status, or steroid treatment. We did not find any significant treatment-related predictive factor for pelvic osteoradionecrosis. Patients with osteoporosis are probably at the highest risk for developing osteoradionecrotic fractures after pelvic radiotherapy. More studies are needed to find out other endogenous predictive factors.  相似文献   
978.
The study analyzes tumor material and normal tissue from 27 patients with pure squamous cell carcinoma of the uterine cervix for loss of heterozygosity (LOH) and microsatellite instability (MSI) on 14 autosomal and 11 X chromosomal loci. Overall, 4-40% of the informative cases showed LOH at autosomal regions with the highest frequency at 3p (21-40%) and a marked frequency at 2q35-q37.1 (12.5%) and 17p13.3 (10%), representing regions with putative tumor suppressor gene (TSG) function. The frequency of X chromosomal LOH ranged from 4% to 20%, with a maximum at Xq28 (20%) and Xq11.2-q12 (17%), again indicating alterations in TSG. A 12% LOH was seen at Xq21.33-q22.3, a region encoding a protein with a regulatory function in the cell cycle via cyclin-dependent kinases. MSI was detected in autosomal regions in up to 7% in regions linked to the X chromosome in up to 11%, probably indicating alterations of mismatch repair mechanisms. Our results and those obtained from the literature suggest that autosomal LOH and MSI in carcinomas of the cervix uteri are predominantly found at regions with putative TSG function. Beside TSG alterations, X chromosomal LOH is probably more strongly connected to disturbances in cell cycle regulation.  相似文献   
979.
980.
In a retrospective study using univariate analysis, we identified tumor type (nonendometrioid vs endometrioid), depth of myoinvasion (MI), mode of MI (infiltrative vs cohesive), and direct anatomic invasion of the cervical wall from the isthmus as significant positive risk factors for intramyometrial lymphvascular space involvement (LVSI). On multivariate analysis, tumor grade, depth of MI, and mode of MI retained their significance. We created a grid for the relative risks of LVSI with respect to these variables individually or in combination. We suggest that our indirect estimate of the risk of LVSI can help in assessing prognosis and determining the need for adjuvant therapy whenever LVSI is important in clinical decision making, but its pathologic diagnosis is uncertain.  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