全文获取类型
收费全文 | 17041篇 |
免费 | 1971篇 |
国内免费 | 295篇 |
专业分类
耳鼻咽喉 | 63篇 |
儿科学 | 234篇 |
妇产科学 | 167篇 |
基础医学 | 1592篇 |
口腔科学 | 337篇 |
临床医学 | 1464篇 |
内科学 | 2464篇 |
皮肤病学 | 157篇 |
神经病学 | 862篇 |
特种医学 | 272篇 |
外国民族医学 | 2篇 |
外科学 | 618篇 |
综合类 | 1684篇 |
一般理论 | 7篇 |
预防医学 | 6922篇 |
眼科学 | 241篇 |
药学 | 1259篇 |
8篇 | |
中国医学 | 188篇 |
肿瘤学 | 766篇 |
出版年
2024年 | 54篇 |
2023年 | 343篇 |
2022年 | 507篇 |
2021年 | 699篇 |
2020年 | 716篇 |
2019年 | 723篇 |
2018年 | 639篇 |
2017年 | 676篇 |
2016年 | 644篇 |
2015年 | 763篇 |
2014年 | 1163篇 |
2013年 | 1531篇 |
2012年 | 1150篇 |
2011年 | 1281篇 |
2010年 | 960篇 |
2009年 | 870篇 |
2008年 | 871篇 |
2007年 | 953篇 |
2006年 | 754篇 |
2005年 | 605篇 |
2004年 | 525篇 |
2003年 | 402篇 |
2002年 | 354篇 |
2001年 | 347篇 |
2000年 | 277篇 |
1999年 | 199篇 |
1998年 | 179篇 |
1997年 | 186篇 |
1996年 | 160篇 |
1995年 | 114篇 |
1994年 | 82篇 |
1993年 | 75篇 |
1992年 | 82篇 |
1991年 | 65篇 |
1990年 | 46篇 |
1989年 | 33篇 |
1988年 | 42篇 |
1987年 | 29篇 |
1986年 | 26篇 |
1985年 | 40篇 |
1984年 | 21篇 |
1983年 | 19篇 |
1982年 | 20篇 |
1981年 | 20篇 |
1980年 | 19篇 |
1979年 | 12篇 |
1978年 | 7篇 |
1977年 | 13篇 |
1976年 | 4篇 |
1969年 | 2篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
151.
F. Brugnone L. Perbellini G. Z. Wang G. Maranelli E. Raineri E. De Rosa C. Saletti C. Soave L. Romeo 《International archives of occupational and environmental health》1993,65(2):125-130
Summary Blood styrene was measured by a gas chromatography-mass spectrometry method in 81 normal people and in 76 workers exposed to styrene. In the normal subjects, styrene was also tested in alveolar and environmental air. Styrene was found in nearly all (95%) blood samples. Average styrene levels in the normal subjects were 221 ng/1 in blood (Cb), 3 ng/1 in alveolar air (Ca) and 6 ng/1 in environmental air (Ci). Styrene levels did not differ significantly between smokers and non-smokers, 95% of values being below 512 ng/1 in Cb, 7 ng/1 in Ca and 15 ng/l in Ci. In workers with an average exposure to styrene of 204 g/l, at the end of the workshift, mean blood styrene concentration was 1211 g/l. In blood samples collected at the end of the Thursday shift, styrene levels were significantly higher (1590 g/1) than those found at the end of the Monday shift (1068 g/l. A similar difference was found in samples taken the morning after exposure (60 and 119 g/l, respectively). Significant correlations between blood and environmental styrene were found both at the end of the shift and the morning after exposure (r=0.61 and 0.41, respectively). In workers occupationally exposed to styrene, 16 h after the end of the workshift, blood styrene (94 g/l) was significantly higher than that found in the normal subjects (0.22 g/l). The half-life of blood styrene was 3.9 h. 相似文献
152.
Takao Watanabe Okujou Iwani Shinichiro Shimbo Masayuki Ikeda 《International archives of occupational and environmental health》1993,65(Z1):S205-S208
Blood samples and 24-h duplicates of food were collected in the years around 1980 and then in 1990's from inhabitants of nonpolluted regions in Japan. The 1990 study is still in progress with 286 blood samples and 125 food duplicates already collected from 7 regions. A preliminary analysis is made in the present study with the data obtained from the 7 study regions where the survey was conducted in 1980 and then in 1990, to examine possible changes in dietary cadmium intake (Cd-D) and consequently cadmium levels in blood (Cd-B) during this 10 year period. The food duplicate analysis showed that Cd-D in 1980 was 47.1 g/day (1.74):65 [GM (GSD):N] for men and 27.7 g/day (1.75):65 for women. The counterpart values in 1990 were 29.5 g/day (1.66):40 for men and 23.8 g/day (1.73):85 for women; the difference between the two values for the same sex is significant (P<0.05) both=" in=" men=" and=" in=" women,=" suggesting=" that=" there=" occurred=" about=" 37%=" and=" 14%=" reduction=" in=" dietary=" cadmium=" intake=" during=" this=" 10=" year=" period=" in=" men=" and=" in=" women,=" respectively.=" comparison=" in=" cd-b=" showed=" that=" cd-b=" for=" men=" and=" women=" in=" 1990=" were=" 1.79=">0.05)>g/l (2.01):121 and 1.84 g/l; (1.67):165, respectively, whereas the counterpart values in 1980 were 3.84 g/l (1.64):123 and 3.57 g/l (1.42):141, respectively, indicating significant (P<0.01) reduction=" in=" cd-b=" in=" both=" sexes=" in=" parallel=" to=" the=" reduction=" in=" cd-d.=" the=" role=" of=" rice=" as=" a=" major=" source=" of=" cadmium=" among=" japanese=" population=" together=" with=" recent=" reduction=" in=" the=" importance=" is=" discussed;=" cd=" in=" rice=" accounted=" for=" 72%=" in=" late=" 1970's,=" whereas=" it=" is=" about=" 35%=" in=" the=" present=">0.01)> 相似文献
153.
目的:为了能在自然界大型水体和旷野中对中华按蚊种群进行研究。方法:研制出适合于稻田浅水定量研究的实验简,适合于深水的实验网和接近自然状态的大实验笼。应用这些工具进行了自然界中华按蚊种群生命表的研究。结果:利用系列研究工具定量研究出1988年第8代中华按蚊自然种群生命表。求出各发育历期的死亡数和死亡因素,死亡率,存活率和死亡因素k值,分析出各发育阶段的关键死亡因素,计算下代预计产卵量为8288粒,种群趋势指数I为6.3027。结论:系列研究工具使中华按蚊自然种群的定量研究成为可能。郑州中华按蚊第9代种群数量还趋于增加之中。 相似文献
154.
目的探讨自然界内郑州中华按蚊种群的繁衍动力学。方法采用自然调查和数学生态学的方法。结果求出自然界郑州中华按蚊1998年第6代的净增殖率Ro为3.522O,平均世代周期T为22.9420d,增长能力rc为O.0549,有限增殖速率λ为1.0564,种群增长1倍的时间t为12.6256d,雌蚊预期寿命ex为5.5加3d,瞬时出生率b为0.0620,瞬时死亡率d为0.0071,稳定年龄组配中未成熟期占98.2988%,成蚊占1.7012%。结论该研究为自然界中华按蚊种群的预测预报及防蚊灭疟策略的制订提供了可靠的科学依据。 相似文献
155.
目的:研究新近报道的一种与输血后肝炎有关的病毒在中国郑州地区正常人群、HBsAg阳性者、非甲至非戊型肝炎患者中的感染和基因序列变异情况。方法:采用TTV基因组ORF1区的套式聚合酶链反应(nested-PCR)方法对血清标本进行检测,并对非甲至非戊型肝炎患者中的TTV分离株进行序列测定。结果:TTV DNA在非甲至非戊型肝炎患者中检出率为45%(18/40);在正常体检者中检出率为17.7%(17/96);在HBsAg阳性者(ALT≤34 IU/L)中检出率22.7%(10/44)。TTV分离株序列与日本株(CLON22)相对应位置的核苷酸同源性为.1%。结论:TTV在非甲至非戊型肝炎患者TTV的感染率明显高于其他人群,可能是非甲至非戊型肝炎的主要致病因子。 相似文献
156.
老年人生活满意度与生存质量关系的探讨 总被引:12,自引:0,他引:12
目的 分析和探讨老年人生活满意度和生存质量的相互关系。方法 对福州市1084例年龄≥60岁的老年人进行生活满意度和生存质量地流行病学调查,将两组数据分别采用因子分析法和典型相关分析法进行分析。结果 生活满意度与生存质量呈正相关关系;生存质量的高低主要由生活满意度来反映。结论提高生活满意度是改善生存质量的重要措施。 相似文献
157.
Nadia Falah Alissa Terry Amna Umer Marlee Kastner Kathryn L. Oliverio Nicole Matthews Kimberly M. Kelly Yvonne Kellar-Guenther 《American journal of medical genetics. Part A》2023,191(4):1013-1019
Telegenetics has shifted some genetic testing performance to the patient's own home, with the patient collecting his/her own sample. Little is known regarding the rate of test completion of such home-based genetic testing. This study compared the completion rate of home-based genetic tests before and after a reminder system was implemented. In the pre-reminder group, we reviewed medical records for patients who were seen via telegenetics and agreed to complete genetic testing using an at-home test kit. In the reminder group, a prospective analysis of the genetic test completion rate was performed taking a clinical quality improvement approach where three reminders were provided for patients who had not submitted their at-home genetic testing. Our study included 94 patients' records: 46 pre-reminders and 48 reminders. The lab received 24 patient samples (52.2%) in the pre-reminder group. In the reminder group, 30 patients returned their kits (62.5%). Despite a higher percentage of patients completing their test in the reminder group, there was no statistically significant difference between the pre-reminder and reminder groups. The rate of test completion in our pilot test was statistically similar between the two groups, but the reminder group was trending toward a higher percent of completion which may be clinically meaningful. 相似文献
158.
Huang FY 《Maternal and child health journal》1997,1(2):69-80
Objectives: This study assesses the health insurance coverage of children of immigrants in the United States and variations among immigrant groups. Method: The study uses data from the March supplements of the 1994 and 1996 Current Population Survey to compare health insurance coverage of children who report foreign parentage. Separate logistic regressions are conducted to estimate the likelihood of being covered by any insurance, public insurance, and private insurance. Results: 27.3% of all children of immigrants are without health insurance, 34.1% are on public insurance, and 44.3% have private insurance. Foreign-born children who have not yet become U.S. citizens are the most likely to be without health insurance (38.0%). Many of these children are not covered because their parents are unable to find jobs that provide coverage and Medicaid fails to enroll as many of them as possible. Overall, the children's chances of being covered by any health insurance vary little according to when their parents came to this country. However, children of recent immigrants are more likely to rely on public health insurance (40.1% vs. 24.8%) and less likely to be covered through private sources (36.8% vs. 60.6%) than those of established immigrants. Among immigrant groups, children of Haitian (48.4%) and Korean (45.3%) immigrants are at the highest risks of being uninsured. Both children of the Dominican Republic (65.9%) and Laos (83.3%) report high rates of public insurance coverage. Conclusions: Greater disparity in health insurance coverage among children of immigrants is expected once the new welfare reform bills take effect. In particular, noncitizen children, children of recent immigrants, illegal immigrants, and Dominican Republican immigrants will be affected most. Efforts aimed at reducing the harm should target these vulnerable groups. 相似文献
159.
我国高砷饮水的地理分布与暴露人群 总被引:10,自引:1,他引:9
根据我国饮水水质与水性疾病调查资料,统计了我国高砷饮水的地理分布和暴露人群。从28800多份水样测定得出:我国饮水中砷浓度0.030~0.049mg/L的饮用人口为902万人;水砷浓度为0.050~0.099mg/L的饮用人口为334万人;而水砷浓度>0.1mg/L的饮用人口为229万人。全国大约有1460万人受到来自饮水砷(>0.030mg/L)的暴露,占调查区人口的1.5%。高砷饮水主要是地下水。本文表列了各省、自治区、直辖市的饮水砷浓度状况,图示了这些高砷水的地理分布。 相似文献
160.
Data from analgesic clinical trials have characteristics such as ordered categorical longitudinal responses with repeated measures, delay of effect with respect to analgesic plasma concentration, and right-hand censoring of response due to remedication. In order to determine the concentration-effect relationship of such data, we propose convolving an empirical function for plasma concentration, in the form of broken lines which connect each pair of neighboring observations, with a monoexponential function, to generate effect site concentration Effect site concentration and time are used, simultaneously, as independent variables in the fit of the model for the logit of the probability of having a specific pain relief (PR) score at each time point pre-remedication, via maximum likelihood. Using corresponding effect site concentration, the probabilities of having specific PR scores post-remedication are predicted via the concentration-response relationship established. The overall (pre- and post-remedication) predictions and corresponding standard errors for the responses are then estimated. Inference of the PR scoring, using a posterior method, is proposed. An illustration using real data is used to demonstrate these methods. 相似文献