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   10649篇
  免费   965篇
  国内免费   15篇
  2023年   44篇
  2021年   159篇
  2020年   128篇
  2019年   165篇
  2018年   233篇
  2017年   218篇
  2016年   314篇
  2015年   547篇
  2014年   561篇
  2013年   703篇
  2012年   869篇
  2011年   769篇
  2010年   515篇
  2009年   472篇
  2008年   678篇
  2007年   625篇
  2006年   542篇
  2005年   511篇
  2004年   464篇
  2003年   427篇
  2002年   399篇
  2001年   202篇
  2000年   185篇
  1999年   153篇
  1998年   94篇
  1997年   77篇
  1996年   53篇
  1995年   83篇
  1994年   52篇
  1993年   57篇
  1992年   96篇
  1991年   81篇
  1990年   88篇
  1989年   99篇
  1988年   93篇
  1987年   81篇
  1986年   72篇
  1985年   80篇
  1984年   57篇
  1983年   47篇
  1982年   37篇
  1981年   29篇
  1980年   39篇
  1979年   56篇
  1978年   48篇
  1977年   35篇
  1976年   44篇
  1975年   35篇
  1974年   35篇
  1973年   28篇
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
1.
There is considerable need for accurate suicide risk assessment for clinical, screening, and research purposes. This study applied the tripartite affect-behavior-cognition theory, the suicidal barometer model, classical test theory, and item response theory (IRT), to develop a brief self-report measure of suicide risk that is theoretically-grounded, reliable and valid. An initial survey (n = 359) employed an iterative process to an item pool, resulting in the six-item Suicidal Affect-Behavior-Cognition Scale (SABCS). Three additional studies tested the SABCS and a highly endorsed comparison measure. Studies included two online surveys (Ns = 1007, and 713), and one prospective clinical survey (n = 72; Time 2, n = 54). Factor analyses demonstrated SABCS construct validity through unidimensionality. Internal reliability was high (α = .86-.93, split-half = .90-.94)). The scale was predictive of future suicidal behaviors and suicidality (r = .68, .73, respectively), showed convergent validity, and the SABCS-4 demonstrated clinically relevant sensitivity to change. IRT analyses revealed the SABCS captured more information than the comparison measure, and better defined participants at low, moderate, and high risk. The SABCS is the first suicide risk measure to demonstrate no differential item functioning by sex, age, or ethnicity. In all comparisons, the SABCS showed incremental improvements over a highly endorsed scale through stronger predictive ability, reliability, and other properties. The SABCS is in the public domain, with this publication, and is suitable for clinical evaluations, public screening, and research.  相似文献   
2.
The results of the investigations of radioactive contamination after the Chernobyl catastrophe and subsequent iodine prophylaxis on the thyroid gland function and morphology in Northeast Poland. The aim of the study was to determine whether kalium iodine in one dose during radioactive contamination in Poland limited the radioactive dose in the thyroid gland and if significant disadvantageous side-effects in the intrathyroid and extrathyroid occurred. Additionally during the studies we tried to determine if radioactive iodine contamination which occurred in the region of the Medical Academy in Bia?ystok caused an increase in thyroid disease. It is interesting to note the different results obtained after radioactive contamination with the results from the investigations in this same territory in 1983-1985. In 1983-1985, before the Chernobyl catastrophe, 6,921 persons in Northeast Poland were investigated. In 1986-1988, immediately after the disaster 4,010 persons were investigated. The main study according to grant No MZ-XVII was carried out in three provinces: Bia?ystok, Suwa?ki and Olsztyn. In this investigation 10,011 persons born before April 26, 1986 and after January 1, 1936 participated, 5,789 townspeople and 4,222 villagers, 3,987 children up to 16 years of age it the time of the disaster 1,973 boys and 2,009 girls; 6,024 adults 2,509 men and 3,516 women were drawn from a register. Committed doses to the thyroid in the investigated region were one of the highest in Poland and depended on age group and were depended on time of prophylaxis non proportional. Iodine prophylaxis was provided mainly with one dose of Lugol solution about 90%, 95% children and 30% adults took iodine. The majority of the population (53.3%-74%) were given iodine in April. From May 1st to 5th 23.0-43.4% received iodine, but after May 5th very few persons. Iodine was well tolerated, but Lugol Solution was better tolerated than other kinds of iodine. Only 241 (4.4%) cases had side effects, mainly vomiting (143), symptoms such as stomach ache, diarrhea, dyspnoe, skinrash etc. in lesser numbers. 12% (29 persons) were seen by a physician. In the investigated population were 200 pregnant women aged 19-40 years of which the majority (177) delivered full term healthy babies. Only 1 interrupted pregnancy and 7 had spontaneous abortion. Changes in the thyroid were noticed by 187 persons (2.3%-11.7%) most of which were enlargement of the thyroid, but only a few were confirmed by a physician. In the studied population from 1989 to 1990 over 30% of the population had struma.(ABSTRACT TRUNCATED AT 400 WORDS)  相似文献   
3.
A 45-year-old-male who had underlying ulcerative colitis and presented with fever and dry cough. Initially, the patient was considered to have invasive aspergillosis due to a positive galactomannan assay. He was treated with amphotericin B followed by voriconazole. Nevertheless, the patient deteriorated clinically and radiographically. The lung biopsy revealed eosinophilic pneumonia, and ELISA for Toxocara antigen was positive, leading to a diagnosis of pulmonary toxocariasis. After a 10-day treatment course with albendazole and adjunctive steroids, the patient recovered completely without any sequelae. Pulmonary toxocariasis may be considered in patients with subacute or chronic pneumonia unresponsive to antibiotic agents, particularly in cases with eosinophilia.  相似文献   
4.
5.
6.

1. 1. The objective of this paper is to investigate the indoor environment from the viewpoint of interaction between physical environment and the human responses. The field survey has been conducted over 1 year.

2. 2. A continuous measurement has been carried out for 1 week and distribution of variables have been measured for 1 day.

3. 3. The attitude of workers was investigated by a questionnaire.

4. 4. As the result, average luminance represented more than 1000 lx in the new building, in contrast with less tha 300 lx in the existing building.

5. 5. There was a significant difference of the occupants' response to the light environment between the two buildings.

6. 6. Measured thermal conditions are on the edge of the ASHRAE comfort envelope in summer, and in the neighborhood of the lower dry limit of the envelope in spring.

7. 7. The occupants' evaluations were remarkably changed before and after the moving. The office environment is better than that of the factory.

Author Keywords: Office; post occupancy evaluation; physical environmental condition; occupants' evaluation  相似文献   

7.
8.
In this paper, we propose an adversary model to facilitate forensic investigations of mobile devices (e.g. Android, iOS and Windows smartphones) that can be readily adapted to the latest mobile device technologies. This is essential given the ongoing and rapidly changing nature of mobile device technologies. An integral principle and significant constraint upon forensic practitioners is that of forensic soundness. Our adversary model specifically considers and integrates the constraints of forensic soundness on the adversary, in our case, a forensic practitioner. One construction of the adversary model is an evidence collection and analysis methodology for Android devices. Using the methodology with six popular cloud apps, we were successful in extracting various information of forensic interest in both the external and internal storage of the mobile device.  相似文献   
9.
A recombinant cell line (NIH3T3:pLtkSN) was made by infecting parental cells (NIH3T3) with a recombinant retrovirus (pLtkSN) encoding herpes simplex virus thymidine kinase (HSVtk) gene. The cells expressing HSVtk (NIH3T3:pLtkSN) grew 2.3 times more than the parental cells (NIH3T3) in Dulbecco's Modified Eagles Media containing 10% (v/v) horse serum. The NIH3T3:pLtkSN cells also showed a significant enhancement in the maximal cell concentration and the specific growth rate even at 2.5% serum concentration. The specific O2 uptake rate of NIH3T3 was 2.1 times greater than that of NIH3T3:pLtkSN. Under both O2-limited and O2-unlimited conditions, it appears that HSVtk plays an important role in enhancing the growth characteristics of animal cells.  相似文献   
10.
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