全文获取类型
收费全文 | 2748篇 |
免费 | 192篇 |
国内免费 | 4篇 |
专业分类
耳鼻咽喉 | 41篇 |
儿科学 | 103篇 |
妇产科学 | 64篇 |
基础医学 | 381篇 |
口腔科学 | 146篇 |
临床医学 | 299篇 |
内科学 | 448篇 |
皮肤病学 | 55篇 |
神经病学 | 297篇 |
特种医学 | 79篇 |
外科学 | 271篇 |
综合类 | 9篇 |
预防医学 | 253篇 |
眼科学 | 16篇 |
药学 | 328篇 |
中国医学 | 3篇 |
肿瘤学 | 151篇 |
出版年
2023年 | 15篇 |
2022年 | 30篇 |
2021年 | 60篇 |
2020年 | 50篇 |
2019年 | 49篇 |
2018年 | 69篇 |
2017年 | 52篇 |
2016年 | 61篇 |
2015年 | 53篇 |
2014年 | 82篇 |
2013年 | 132篇 |
2012年 | 156篇 |
2011年 | 171篇 |
2010年 | 103篇 |
2009年 | 105篇 |
2008年 | 147篇 |
2007年 | 166篇 |
2006年 | 153篇 |
2005年 | 128篇 |
2004年 | 140篇 |
2003年 | 132篇 |
2002年 | 122篇 |
2001年 | 45篇 |
2000年 | 39篇 |
1999年 | 35篇 |
1998年 | 25篇 |
1997年 | 23篇 |
1996年 | 22篇 |
1995年 | 24篇 |
1994年 | 23篇 |
1993年 | 16篇 |
1992年 | 36篇 |
1991年 | 29篇 |
1990年 | 25篇 |
1989年 | 27篇 |
1988年 | 27篇 |
1987年 | 32篇 |
1986年 | 40篇 |
1985年 | 22篇 |
1984年 | 27篇 |
1983年 | 19篇 |
1979年 | 23篇 |
1978年 | 19篇 |
1975年 | 15篇 |
1974年 | 12篇 |
1972年 | 16篇 |
1971年 | 17篇 |
1970年 | 18篇 |
1969年 | 16篇 |
1967年 | 13篇 |
排序方式: 共有2944条查询结果,搜索用时 46 毫秒
41.
John C. Morrison Kyle Steffen Blake Pantoja Asha Nagaiya Jacek Kobus & Thomas Ericsson 《Communications In Computational Physics》2016,19(3):632-647
In order to solve the partial differential equations that arise in the Hartree-Fock
theory for diatomic molecules and in molecular theories that include electron correlation,
one needs efficient methods for solving partial differential equations. In this
article, we present numerical results for a two-variable model problem of the kind that
arises when one solves the Hartree-Fock equations for a diatomic molecule. We compare
results obtained using the spline collocation and domain decomposition methods
with third-order Hermite splines to results obtained using the more-established finite
difference approximation and the successive over-relaxation method. The theory of
domain decomposition presented earlier is extended to treat regions that are divided
into an arbitrary number of subregions by families of lines parallel to the two coordinate
axes. While the domain decomposition method and the finite difference approach
both yield results at the micro-Hartree level, the finite difference approach with a 9-point difference formula produces the same level of accuracy with fewer points. The
domain decomposition method has the strength that it can be applied to problems with
a large number of grid points. The time required to solve a partial differential equation
for a fine grid with a large number of points goes down as the number of partitions
increases. The reason for this is that the length of time necessary for solving a set of
linear equations in each subregion is very much dependent upon the number of equations.
Even though a finer partition of the region has more subregions, the time for
solving the set of linear equations in each subregion is very much smaller. This feature
of the theory may well prove to be a decisive factor for solving the two-electron pair
equation, which – for a diatomic molecule – involves solving partial differential equations
with five independent variables. The domain decomposition theory also makes
it possible to study complex molecules by dividing them into smaller fragments thatare calculated independently. Since the domain decomposition approach makes it possible
to decompose the variable space into separate regions in which the equations are
solved independently, this approach is well-suited to parallel computing. 相似文献
42.
Höök H Ekegren MB Ericsson H Vågsholm I Danielsson-Tham ML 《Scandinavian journal of infectious diseases》2004,36(6-7):435-442
84 Campylobacter jejuni isolates from Swedish patients with domestic infection were characterized with pulsed-field gel electrophoresis (PFGE), and the subtype information considered in relation to epidemiological data. Based on pattern combinations from restriction cleavage with SmaI and SalI, 52 different PFGE types were identified. Types with an average pattern similarity of at least 82% and 63% were assembled in groups and clusters, respectively. The 2 largest clusters included 71% of the isolates. The distribution in time varied between different groups and clusters, where some were isolated sporadically during the whole period and others appeared more concentrated in time. Types in 1 cluster were significantly more often isolated in summer than other types in the study. Isolates from children showed lower pattern similarity to other isolates than isolates from adults. Sets of type and time related cases, possibly representing small outbreaks, were identified when indistinguishable PFGE patterns were found in isolates from temporally related cases. Our results indicate that although a large number of genotypes may be found among C. jejuni strains infecting humans, a large proportion of these may be genetically related, and that different genotypes may appear during different seasons and infect individuals of different ages. 相似文献
43.
OBJECTIVES: COPD is a common and disabling disease that entails high costs for society. The objectives of this study were to measure the societal costs of COPD in Sweden, and to examine the relationship between severity of illness and costs. METHODS: The costs of COPD were examined using a well-defined and representative cohort of subjects with mild, moderate, and severe COPD. Regular telephone interviews regarding resource utilization were made to a cohort of 212 subjects with COPD derived from studies of the general population in Northern Sweden. RESULTS: The annual per capita cost for COPD in Swedish crowns (SEK) was estimated at SEK 13,418 (1,284 US dollars (USD); 1,448 euros (EUR). The direct and indirect costs were SEK 5,592 (42%) and SEK 7,828 (58%), respectively. A highly significant relationship was found between severity of disease and costs. Costs for severe disease were 3 times as high as costs for moderate disease and > 10 times as high as for mild disease. Large individual variations in the level of costs were found. CONCLUSION: Assuming that the prevalence and treatment patterns are representative of Sweden as a whole, the total costs of COPD to society in 1999 were estimated at SEK 9.1 billion (USD 871 million; EUR 982 million). Subjects with mild disease (83%) accounted for 29%, while subjects with moderate disease (13%) accounted for 41% of the total costs. The subjects with severe disease (4%) accounted for the remainder (30%). Prevention, early diagnosis, and postponement of disease progression should have large monetary and policy implications. 相似文献
44.
Andrea Zanichelli Markus Magerl Hilary J. Longhurst Werner Aberer Teresa Caballero Laurence Bouillet Anette Bygum Anete S. Grumach Jaco Botha Irmgard Andresen Marcus Maurer the IOS Study Group 《Clinical and translational allergy》2018,8(1):42
The objective of this analysis was to evaluate the change over time in age at first symptoms, age at diagnosis, and delay in diagnosis using data from the Icatibant Outcome Survey (IOS). Patients with a diagnosis of C1-INH-HAE who were born before the year 1990 and who were diagnosed before they reached 25 years of age were included in the analysis. Both age at diagnosis and delay in diagnosis of C1-INH-HAE appear to decline with later decade of birth, despite wide variation across the countries assessed, suggesting that improved disease awareness causes increased rates of earlier diagnosis over time. Our findings demonstrate that some patients are still experiencing long delays to diagnosis, indicating an ongoing need for improved disease awareness. 相似文献
45.
46.
47.
Andreas D Meid Anette Lampert Alina Burnett Hanna M Seidling Walter E Haefeli 《British journal of clinical pharmacology》2015,80(4):768-776
Aims
The aim of the present study was to conduct a meta-analysis of controlled trials assessing the impact of pharmaceutical care interventions (e.g. medication reviews) on medication underuse in older patients (≥65 years).Methods
The databases MEDLINE and EMBASE were searched for controlled studies, and data on interventions, patient characteristics and exposure, and outcome assessment were extracted. Risk of bias was assessed using the Cochrane Collaboration’s ‘risk of bias’ table. Results from reported outcomes were synthesized in multivariate random effects meta-analysis, subgroup meta-analysis and meta-regression.Results
From 954 identified articles, nine controlled studies, mainly comprising a medication review, were included (2542 patients). These interventions were associated with significant reductions in the mean number of omitted drugs per patient (estimate from six studies with 1469 patients: – 0.44; 95% confidence interval –0.61, –0.26) and the proportion of patients with ≥1 omitted drugs (odds ratio from eight studies with 1833 patients: 0.29; 95% confidence interval 0.13, 0.63). The only significant influential factor for improving success was the utilization of explicit screening instruments when conducting a medication review (P = 0.033).Conclusion
Pharmaceutical care interventions, including medication reviews, can significantly reduce medication underuse in older people. The use of explicit screening instruments alone or in combination with implicit reasoning is strongly recommendable for clinical practice. 相似文献48.
Schmidt BM Martin N Georgens AC Tillmann HC Feuring M Christ M Wehling M 《The Journal of clinical endocrinology and metabolism》2002,87(4):1681-1686
T(3) has been shown to exert cardiovascular effects. These effects have not yet been defined with regard to the mode of action (nongenomic vs. genomic) and with regard to an interaction with the adrenergic system in humans. To address these issues we conducted a randomized, double blind, 6-fold cross-over trial in 18 healthy male volunteers. After pretreatment with the beta-agonist dobutamine, the beta-blocking agent esmolol, or placebo (0.9% NaCl), 100 microg T(3) or placebo were injected. Primary target variables were systemic vascular resistance (SVR) and cardiac output (CO) within 45 min after injection of T(3) vs. placebo after placebo pretreatment. Sympatho-vagal balance was assessed by measurement of heart rate variability. T(3) caused a lower SVR and a higher CO than placebo (P < 0.001) after pretreatment with placebo. An increased low frequency (LF)/high frequency (HF) ratio (power in LF/power in HF band) after T(3) compared with placebo (P = 0.004) suggests an increase in sympathetic tone. After pretreatment with dobutamine, the effects of T(3) on SVR and CO were abolished, and the effect on LF/HF ratio was reversed. After pretreatment with esmolol, the effects on SVR and LF/HF ratio were reversed. Our data show, for the first time, nongenomic cardiovascular effects of T(3) in humans. 相似文献
49.
Jenny Mullen Lasse Vestli Bkken Timo Trmkangas Lena Ekstrm Magnus Ericsson Ingunn R. Hullstein Jenny J. Schulze 《Drug testing and analysis》2020,12(6):720-730
The steroidal module of the Athlete Biological Passport (ABP) aims to detect doping with endogenous steroids, e.g. testosterone (T), by longitudinally monitoring several biomarkers. These biomarkers are ratios combined into urinary concentrations of testosterone and metabolically related steroids. However, it is evident after 5 years of monitoring steroid passports that there are large variations in the steroid ratios complicating its interpretation. In this study, we used over 11000 urinary steroid profiles from Swedish and Norwegian athletes to determine both the inter‐ and intra‐individual variations of all steroids and ratios in the steroidal passport. Furthermore, we investigated if the inter‐individual variations could be associated with factors such as gender, type of sport, age, time of day, time of year, and if the urine was collected in or out of competition. We show that there are factors reported in today's doping tests that significantly affect the steroid profiles. The factors with the largest influence on the steroid profile were the type of sport classification that the athlete belonged to as well as whether the urine was collected in or out of competition. There were also significant differences based on what time of day and time of year the urine sample was collected. Whether these significant changes are relevant when longitudinally monitoring athletes in the steroidal module of the ABP should be evaluated further. 相似文献
50.
Tobias Sieckmann Hatem Elmongy Magnus Ericsson Hasanuzzaman Bhuiyan Mikael Lehtihet Lena Ekstrm 《Drug testing and analysis》2020,12(6):711-719
The detection of low doses of recombinant growth hormone is a challenge in antidoping testing. Future testing may lead toward the longitudinal monitoring of IGF‐I and P‐III‐NP in an endocrine module. Additional biomarkers, for example vitamin D binding protein, alpha‐HS‐glycoprotein, fibronectin 1, and decorin have been identified in different omics studies. This was a longitudinal study of the usefulness of these putative biomarkers in relation to 2 weeks administration of low doses of recombinant growth hormone in healthy male volunteers. Moreover, the hematological parameters included in the athlete biological passport were studied as well as the serum concentration of testosterone and dihydrotestosterone. Fibronectin 1 increased by 20% during the treatment period (P ? 0.05), confirming the previous finding. Alpha‐HS‐glycoprotein decreased by 25% up to 3 weeks after treatment (P ? 0.05), contradicting previous results. The addition of fibronectin 1 increased the likelihood of detecting recombinant growth hormone intake based on individual calculated thresholds in some of the participants compared with the GH2000, IGF‐I, and P‐III‐NP. The multiplication of fibronectin 1 concentration by IGF‐I resulted in the most profound (up to 4‐fold) changes. A minor 15% increase (P = 0.003) in the reticulocyte percentage was observed, but the changes did not lead to any atypical profile based on individual passport thresholds. Vitamin D binding protein, decorin, testosterone, and dihydrotestosterone were not affected by growth hormone. Dihydrotestosterone sulfate was negatively correlated with IGF‐I at baseline (R = –0.50, P = 0.003) and post dose (R = –0.59, P = 0.01). In conclusion, fibronectin 1 was verified as a promising future biomarker for detecting low doses of recombinant growth hormone. 相似文献