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   14872篇
  免费   1891篇
  国内免费   357篇
耳鼻咽喉   92篇
儿科学   167篇
妇产科学   610篇
基础医学   682篇
口腔科学   251篇
临床医学   1908篇
内科学   1873篇
皮肤病学   117篇
神经病学   308篇
特种医学   282篇
外国民族医学   22篇
外科学   1846篇
综合类   2350篇
预防医学   782篇
眼科学   162篇
药学   1208篇
  18篇
中国医学   981篇
肿瘤学   3461篇
  2024年   42篇
  2023年   299篇
  2022年   462篇
  2021年   864篇
  2020年   853篇
  2019年   681篇
  2018年   636篇
  2017年   752篇
  2016年   773篇
  2015年   724篇
  2014年   1154篇
  2013年   1188篇
  2012年   1017篇
  2011年   1122篇
  2010年   756篇
  2009年   716篇
  2008年   690篇
  2007年   685篇
  2006年   595篇
  2005年   484篇
  2004年   419篇
  2003年   365篇
  2002年   281篇
  2001年   249篇
  2000年   206篇
  1999年   178篇
  1998年   155篇
  1997年   103篇
  1996年   90篇
  1995年   99篇
  1994年   67篇
  1993年   51篇
  1992年   49篇
  1991年   39篇
  1990年   40篇
  1989年   32篇
  1988年   33篇
  1987年   27篇
  1986年   19篇
  1985年   24篇
  1984年   20篇
  1983年   20篇
  1982年   20篇
  1981年   16篇
  1980年   9篇
  1979年   4篇
  1978年   6篇
  1976年   2篇
  1975年   2篇
  1966年   1篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
91.
Live human germ cells in the context of their spermatogenic stages   总被引:2,自引:0,他引:2  
BACKGROUND: Various types of live, dispersed, human testicular cells in vitro were previously compared with the morphologic characteristics of human spermatogenic germ cells in situ within seminiferous tubules. The current study extends those observations by placing live human germ cells in the context of their developmental steps and stages of the spermatogenic cycle. METHODS: Live human testicular tissue was obtained from an organ-donating, brain-dead person. A cell suspension was obtained by enzymatic digestion, and dispersed cells were observed live with Nomarski optics. Testes from 10 men were obtained at autopsy within ten hours of death, fixed in glutaraldehyde, further fixed in osmium, embedded in Epon, sectioned at 20 microm, and observed unstained by Nomarski optics. RESULTS: In both live and fixed preparations, Sertoli cells have oval to pear-shaped nuclei with indented nuclear envelopes and large nucleoli, which makes their appearance distinctly different from germ cells. For germ cells, size, shape, and chromatic pattern of nuclei, the presence of meiotic metaphase figures, acrosomic vesicles/structures, tails, and/or mitochondria in the middle piece are characteristically seen in live dispersed cells and those in the fixed seminiferous tubules. These lead to identification of live germ cells in man and placement of each in the context of their developmental steps of spermatogenesis at corresponding stages of the spermatogenic cycle. CONCLUSIONS: This comparative approach allows verification of the identity of individual germ cells seen in vitro and provides a checklist of distinguishing characteristics of live human germ cells to be used in clinical procedures or by scientists interested in studying live cells at known steps in spermatogenic development characteristic of germ cells in specific stages of the spermatogenic cycle.  相似文献   
92.
To examine the vasculature of the areola-gland subunit of advanced pig placenta, tissues from ten animals between 43 and 112 days of gestation were prepared for histology and for scanning electron microscopy of vascular corrosion casts from both maternal and fetal sides. Regular areolae, tributary to one gland only, are round with a wide-meshed and smooth subepithelial capillary network on the maternal side, which is similar to the pre-implantative stage and bordered by an abrupt rim towards the interareolar maternal capillary network. On the fetal side, the capillary network follows papillae which protrude into the areolar cavity or converge to form a ring towards the areolar periphery. Irregular areolae, in contrast, have indistinct boundaries and are characterized by two or more gland openings. The maternal capillary network has moderate density and follows the corrugations, whereas the fetal capillary network is basically two-dimensional with some blunt sinusoidal protrusions. Vessel architecture of both areolar types implies facilitated external inflow of blood into the areola on arteriolar as well as on capillary levels, whereas the outflow from the areolar capillaries comprises venules converging into one or two areolar stem veins, and therefore conducts venous blood in a manner different from that of the interareolar region. It is suggested that this arrangement could favour vascular control mechanisms in uterus, placenta and fetus. On the basis of these observations and the discussion, it is suggested that these areolaspecific vessel systems are important for sustaining the characteristic substance transfers in the areola, the secretion, metabolism and absorption, which according to the literature are not the same in the regular as in the irregular areolar type of the porcine areola-gland subunit of the placenta.  相似文献   
93.
目的:探索脑卒中患者促进上肢运动功能恢复中头针与镜像疗法联合应用的临床价值。方法:选取株洲市中心医院2021年8月至2022年11月期间收治的60例脑卒中后上肢功能障碍患者,以随机分组的方式分为两组,每组30例。其中常规康复训练联合镜像治疗纳入对照组,在对照组基础上增加头针治疗纳入观察组。在治疗4周后,比较两组患者临床治疗有效性、Fugl–meyer运动功能评定量表(FMA)上肢部分评分以及Brunnstrom分期。结果:两组患者治疗后FMA评分均高于治疗前,且观察组患者治疗后FMA评分高于对照组,差异具有统计学意义(P<0.05)。观察组患者治疗后上肢Brunnstrom运动功能分期结果优于对照组,差异具有统计学意义(Z=–2.101,P <0.05)。观察组患者治疗后手Brunnstrom运动功能分期结果优于对照组,差异具有统计学意义(Z=–2.152,P <0.05)。结论:在恢复早期,头针、镜像疗法与常规康复训练有效结合,对脑卒中患者软瘫期上肢运动功能恢复具有积极作用。  相似文献   
94.
The available data on the association between micronutrients in the blood and non-alcoholic fatty liver disease (NAFLD) are limited. To investigate the clinical implications of this relationship, we sought to identify the difference in the serum levels of vitamins A and E according to NAFLD status using data from the seventh Korea National Health and Nutrition Examination Survey. In this cross-sectional study of the Korean population, NAFLD and its severity were defined using prediction models. Differences in the prevalence and severity of NAFLD were analyzed according to serum retinol (vitamin A) and alpha (α)-tocopherol (vitamin E) levels. Serum levels of retinol and α-tocopherol were positively correlated with the prevalence of NAFLD. In most prediction models of the NAFLD subjects, serum retinol deficiency was significantly correlated with advanced fibrosis, while serum α-tocopherol levels did not differ between individuals with or without advanced fibrosis. Similar trends were also noted with cholesterol-adjusted levels of α-tocopherol. In summary, while circulating concentrations of retinol and α-tocopherol were positively associated with the presence of NAFLD, advanced liver fibrosis was only correlated with serum retinol levels. Our findings could provide insight into NAFLD patient care at a micronutrient level.  相似文献   
95.
Nutritional status in oncological patients may differ according to several modifiable and non-modifiable factors. Knowledge of the epidemiology of malnutrition/cachexia/sarcopenia may help to manage these complications early in the course of treatment, potentially impacting patient quality of life, treatment intensity, and disease outcome. Therefore, this narrative review aimed to critically evaluate the current evidence on the combined impact of tumor- and treatment-related factors on nutritional status and to draw some practical conclusions to support the multidisciplinary management of malnutrition in cancer patients. A comprehensive literature search was performed from January 2010 to December 2020 using different combinations of pertinent keywords and a critical evaluation of retrieved literature papers was conducted. The results show that the prevalence of weight loss and associated symptoms is quite heterogeneous and needs to be assessed with recognized criteria, thus allowing a clear classification and standardization of therapeutic interventions. There is a large range of variability influenced by age and social factors, comorbidities, and setting of cures (community-dwelling versus hospitalized patients). Tumor subsite is one of the major determinants of malnutrition, with pancreatic, esophageal, and other gastroenteric cancers, head and neck, and lung cancers having the highest prevalence. The advanced stage is also linked to a higher risk of developing malnutrition, as an expression of the relationship between tumor burden, inflammatory status, reduced caloric intake, and malabsorption. Finally, treatment type influences the risk of nutritional issues, both for locoregional approaches (surgery and radiotherapy) and for systemic treatment. Interestingly, personalized approaches based on the selection of the most predictive malnutrition definitions for postoperative complications according to cancer type and knowledge of specific nutritional problems associated with some new agents may positively impact disease course. Sharing common knowledge between oncologists and nutritionists may help to better address and treat malnutrition in this population.  相似文献   
96.
早期股骨头缺血坏死介入治疗的探讨(附15例报告)   总被引:2,自引:0,他引:2  
目的:探索早期股骨头缺血性坏死的介入治疗方法及效果。方法:采用seldinger穿刺方法超选择插管至患侧旋股内,外动脉,注入治疗药物(溶栓,扩血管,改善微循环等)。介入前后分别血管造影,以观察血管数及近期疗效。结果:介入治疗后患髋股头颈区血管数较治疗前增多(P<0.001),髋关节疼痛缓解,功能改善。结论:对早期股骨头缺血性坏死实施介入治疗,能够改善患髋的血液循环,减轻临床症状,改善关节功能,是一种微创安全有效的新方法,对远期疗效和治疗机理尚有待进一步观察和研究。  相似文献   
97.
维生素D缺乏性晚发性佝偻病的骨密度研究   总被引:1,自引:0,他引:1  
目的:探讨维生素D缺乏性晚发性佝偻病的骨密度变化;方法:采用病例对照研究方法。对640名学生进行问诊及体验,测定非优势侧尺挠骨中1/3交界处骨密度(BMD),病例组检测骨碱性磷酸酶,拍摄腕部X光片,病例组与对照组同测血250HD3;结果:病例组骨密度显著低于对照组,病例组250HD3异常者显著低于对照组;结论:晚佝病是由于维生素D缺乏所至的骨量减少性疾病,日后影响峰值骨量的形成,并与成人期骨质疏松有密切的关系,骨密度检查对晚佝病有重要诊断价值。  相似文献   
98.
王岭  李海燕 《河北医学》2001,7(4):295-297
目的:探讨脑出血急性期血肿扩大的发生率、原因、临床表现、预后及采取的相应措施。方法:回顾性分析1994-2000年间诊治的867例脑出血病人的临床和CT资料。结果:脑出血急性期血肿扩大的发生率为20.1%,其主要与血压增高的程度、凝血功能、出血部位、血肿形态及早期过度脱水有关,血肿扩大增加了病人的死亡率。结论:血肿扩大的发生影响病人预后,应尽早确诊,采取积极防治措施,改善病人预后。  相似文献   
99.
目的 总结皮肤撕脱伤修复后Ⅰ期愈合的治疗效果。方法 早期彻底创面清创,清除所有失去活力的皮肤组织、异物、积血和死腔;根据创面部位、受伤程度选择缝合、皮片、皮瓣移位等不同修复方法修复;早期足量的抗生素应用。结果 1例失败38例成活。Ⅰ期愈合率达97.5%,术后效果满意。结论 本组治疗方法治疗时间短致残率低,Ⅰ期愈合率高,效果满意。  相似文献   
100.
目的:探讨左半结肠癌并梗阻一期切除吻合的可行性。方法:术中灌洗肠内容物,术后吻合口减压。结果:1995年至1999年所遇左侧梗阻性大肠癌中选择5例用此方法吻合成功。结论:左侧梗阻性大肠癌,只要掌握好手术指针。术中充分灌洗肠内容物,术后扩肛可一期切除吻合。  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