全文获取类型
收费全文 | 2400263篇 |
免费 | 196928篇 |
国内免费 | 4282篇 |
专业分类
耳鼻咽喉 | 34607篇 |
儿科学 | 73440篇 |
妇产科学 | 63436篇 |
基础医学 | 337918篇 |
口腔科学 | 67887篇 |
临床医学 | 218417篇 |
内科学 | 473645篇 |
皮肤病学 | 48267篇 |
神经病学 | 203146篇 |
特种医学 | 97023篇 |
外国民族医学 | 886篇 |
外科学 | 364536篇 |
综合类 | 56551篇 |
现状与发展 | 1篇 |
一般理论 | 1013篇 |
预防医学 | 193058篇 |
眼科学 | 55805篇 |
药学 | 179464篇 |
4篇 | |
中国医学 | 4395篇 |
肿瘤学 | 127974篇 |
出版年
2018年 | 25037篇 |
2017年 | 19354篇 |
2016年 | 21146篇 |
2015年 | 23983篇 |
2014年 | 34551篇 |
2013年 | 52258篇 |
2012年 | 70724篇 |
2011年 | 74307篇 |
2010年 | 43544篇 |
2009年 | 41884篇 |
2008年 | 70439篇 |
2007年 | 74837篇 |
2006年 | 75563篇 |
2005年 | 73579篇 |
2004年 | 70815篇 |
2003年 | 68351篇 |
2002年 | 67524篇 |
2001年 | 112644篇 |
2000年 | 116705篇 |
1999年 | 98536篇 |
1998年 | 28106篇 |
1997年 | 25708篇 |
1996年 | 25631篇 |
1995年 | 24739篇 |
1994年 | 23295篇 |
1993年 | 21669篇 |
1992年 | 79488篇 |
1991年 | 76467篇 |
1990年 | 73640篇 |
1989年 | 70928篇 |
1988年 | 65922篇 |
1987年 | 64868篇 |
1986年 | 61391篇 |
1985年 | 58478篇 |
1984年 | 44292篇 |
1983年 | 37729篇 |
1982年 | 22946篇 |
1981年 | 20383篇 |
1979年 | 41343篇 |
1978年 | 29021篇 |
1977年 | 24383篇 |
1976年 | 22867篇 |
1975年 | 23998篇 |
1974年 | 29662篇 |
1973年 | 28065篇 |
1972年 | 26254篇 |
1971年 | 24177篇 |
1970年 | 22768篇 |
1969年 | 21112篇 |
1968年 | 19157篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
N A Zakhari M I Walash M S Rizk S S Toubar C J Brooks W J Cole 《Journal of pharmaceutical and biomedical analysis》1991,9(9):705-709
A simple gas chromatographic procedure has been developed for the determination of methyltestosterone in bulk powders and in tablets. Two new silyl ether derivatives of methyltestosterone have been prepared using dimethylethylsilylimidazole (DMESI) and dimethylisopropylsilylimidazole (DMiPSI). The method is accurate and selective for methyltestosterone within the concentration range 0.1-1.5 micrograms microliters-1. 相似文献
992.
G Hochhaus H Derendorf H M?llmann J Barth 《Journal of pharmaceutical and biomedical analysis》1991,9(9):761-767
A combined LC/RIA procedure is described for the selective determination of dexamethasone (DEX) and its prodrug dexamethasone-21-isonicotinate (DIN) in plasma. The low affinity of the employed dexamethasone antiserum for DIN (cross-reactivity less than 0.5%) allowed the direct determination of DEX in plasma extracts. For the determination of DIN, both substances of interest were separated by LC, the DIN containing fraction was collected, hydrolysed and the generated DEX was consequently assayed by radioimmunoassay. The assay detection limits were 0.1 ng ml-1 for DEX and 0.75 ng ml-1 for DIN. For both substances, inter- and intra-day variabilities (RSDs) were 6 and 12%, respectively. 相似文献
993.
994.
995.
Taylor Moran-Gates Christopher Grady Young Shik Park Ross J Baldessarini Frank I Tarazi 《European neuropsychopharmacology》2007,17(6-7):448-455
The atypical antipsychotic risperidone is often prescribed to pediatric patients with neuropsychiatric disorders, though its effects on the developing brain remain unclear. Accordingly, we studied the effects of repeated treatment of risperidone on dopamine receptors in brain regions of juvenile rat. Levels of dopamine receptors (D(1), D(2), D(3), D(4)) in forebrain regions of juvenile rats were quantified after 3 weeks of treatment with three different doses of risperidone (0.3, 1.0 and 3.0 mg/kg) and compared findings to those in adult rats treated with risperidone (3.0 mg/kg/day) previously. Risperidone (at 1.0 and 3.0 mg/kg/day) increased levels of D(1) receptors in nucleus accumbens and caudate-putamen of juvenile, but not adult rats. Conversely, all three doses of risperidone dose-dependently increased D(2) labeling in medial prefrontal cortex and hippocampus, and D(4) receptor in nucleus accumbens, caudate-putamen and hippocampus of juvenile animals as well as in adults. Only the high dose of risperidone (3.0 mg/kg) increased D(2) receptors in caudate-putamen in both juvenile and adult brain. D(3) receptors were not altered by risperidone in any brain region at any dose or age. The findings indicate dose-dependent effects of risperidone on dopamine receptors in developing animals, and that juvenile animals are more sensitive than adults to the cerebral effects of risperidone. 相似文献
996.
Jeffery H Wootton Anthony B Ross Chris J Diederich 《International journal of hyperthermia》2007,23(8):609-622
PURPOSE: This study was designed to assess pelvic bone temperature during typical treatment regimens of transurethral ultrasound thermal ablation of the prostate to establish guidelines for limiting bone heating. METHODS: Treatment with transurethral planar, curvilinear, and sectored tubular applicators was simulated using an acoustic and biothermal pelvic model that accommodates applicator sweeping, boundary temperature control, and changes in perfusion and attenuation with thermal dose to more accurately model ultrasound energy penetration. The effects of various parameters including power and frequency (5-10 MHz) on bone heating were assessed for a range of prostate cross-sections (3-5 cm) and bone distances (1-3 cm). RESULTS: All devices can produce significant bone heating (temperatures >50 degrees C, thermal dose >240 EM(43 degrees C)) without optimization of applied frequency or power for bone <3 cm from the prostate boundary. In small glands ( approximately 3 cm) increasing operating frequency of curvilinear and planar devices can increase bone temperatures, whereas the tubular applicator can be used at 10 MHz to avoid likely bone damage. In larger prostates (4-5 cm wide) increasing frequency reduces bone heating but can substantially increase treatment time. Lowering power can reduce bone temperature but may increase thermal dose by increasing treatment duration. All applicators can be used to treat glands 4-5 cm with limited bone heating by selecting appropriate power and frequency. CONCLUSIONS: Pubic bone heating during ultrasound thermal therapy of the prostate can be substantial in certain situations. Successful realization of this therapy will require patient-specific treatment planning to optimally determine power and frequency in order to minimize bone heating. 相似文献
997.
E A Cristofalo J A Dipietro K A Costigan P Nelson J Crino 《Journal of perinatology》2006,26(4):215-223
OBJECTIVES: To determine maternal responses to detection of a minor structural variant, the choroid plexus cyst (CPC), in their fetus on prenatal ultrasound. STUDY DESIGN: We interviewed 34 pregnant women with an isolated CPC detected on mid-pregnancy ultrasound about their objective experience at diagnosis, emotional response and subsequent reactions. Audiotaped, transcribed responses were evaluated by two independent raters and analyzed qualitatively and quantitatively. RESULTS: All women reported negative emotional responses including shock, distress, fear and decreased attachment, despite counseling by 82% of providers that the CPC was probably benign. Three women underwent amniocentesis purely for reassurance after CPC detection. Most (79%) sought information beyond what their physician provided, frequently on the internet. One half of women reported that intense negative responses were temporary. However, weeks after diagnosis, 62% continued to believe that the CPC presented some danger to their baby. CONCLUSIONS: Detection of CPC prenatally can evoke profound, negative maternal emotional responses despite accurate provider counseling. Practitioners should consider these responses when counseling parents about these and other structural variants of unclear functional significance. 相似文献
998.
999.
AIM: To undertake a systematic review of the diagnostic performance of clinical examination, sample acquisition and sample analysis in infected foot ulcers in diabetes. METHODS: Nineteen electronic databases plus other sources were searched. To be included, studies had to fulfil the following criteria: (i) compare a method of clinical assessment, sample collection or sample analysis with a reference standard; (ii) recruit diabetic individuals with foot ulcers; (ii) present 2 x 2 diagnostic data. Studies were critically appraised using a 12-item checklist. RESULTS: Three eligible studies were identified, one each on clinical examination, sample collection and sample analysis. For all three, study groups were heterogeneous with respect to wound type and a small proportion of participants had foot ulcers due to diabetes. No studies identified an optimum reference standard. Other methodological problems included non-blind interpretation of tests and the time lag between index and reference tests. Individual signs or symptoms of infection did not prove to be useful tests when assessed against punch biopsy as the reference standard. The wound swab did not perform well when assessed against tissue biopsy. Semiquantitative analysis of wound swab might be a useful alternative to quantitative analysis. The limitations of these findings and their impact on recommendations from relevant clinical guidelines are discussed. CONCLUSION: Given the importance of this topic, it is surprising that only three eligible studies were identified. It was not possible to describe the optimal methods of diagnosing infection in diabetic patients with foot ulceration from the evidence identified in this systematic review. 相似文献
1000.
Early defibrillation along with well performed basic life support (BLS) after cardiac arrest, due to ventricular fibrillation is the gold standard for increasing patients survival. Within Germany there are two standardized schemes for the training of first responders as well as of paramedics, emergency medical technicians etc.; however, the use of public access defibrillation (PAD) is highly variable between localities. Results from the USA as well as from Germany indicate approaches to life-saving issues which need addressing. The paper by Caffrey reveals high regional efficiency for PAD along with BLS, while two German studies show the value of lay individuals in BLS. Zipes (USA) study shows that death due to cardiac arrest occurs at the patient’s home in more than 70%. Two recent, standardized US trials cast doubt on the efficacy of broadly deployed BLS-training programs for lay persons, preferring PAD and BLS training carried out strictly in accordance with the risk-ratio, for instance, of the people near to the first responders. Taking this into account, social insurance for occupational accidents offer qualified first responder training for more than 43 million employees (about half of the Germany population) in more than 3 million companies. It is necessary to find a synthesis between socio-economic demands on the one hand and ethical principles on the other for the emergency medicine network. 相似文献