全文获取类型
收费全文 | 92953篇 |
免费 | 259篇 |
国内免费 | 880篇 |
专业分类
94092篇 |
出版年
2022年 | 1篇 |
2019年 | 1篇 |
2018年 | 11837篇 |
2017年 | 10669篇 |
2016年 | 7444篇 |
2015年 | 579篇 |
2014年 | 271篇 |
2013年 | 280篇 |
2012年 | 4189篇 |
2011年 | 12792篇 |
2010年 | 11988篇 |
2009年 | 8216篇 |
2008年 | 9769篇 |
2007年 | 11348篇 |
2006年 | 245篇 |
2005年 | 496篇 |
2004年 | 954篇 |
2003年 | 1011篇 |
2002年 | 771篇 |
2001年 | 253篇 |
2000年 | 158篇 |
1999年 | 23篇 |
1998年 | 7篇 |
1997年 | 21篇 |
1996年 | 9篇 |
1994年 | 6篇 |
1993年 | 30篇 |
1992年 | 20篇 |
1991年 | 37篇 |
1990年 | 7篇 |
1989年 | 7篇 |
1988年 | 17篇 |
1987年 | 14篇 |
1985年 | 1篇 |
1984年 | 7篇 |
1983年 | 17篇 |
1982年 | 2篇 |
1980年 | 1篇 |
1975年 | 5篇 |
1972年 | 246篇 |
1971年 | 274篇 |
1970年 | 5篇 |
1965年 | 13篇 |
1962年 | 24篇 |
1956年 | 5篇 |
1944年 | 12篇 |
1940年 | 10篇 |
排序方式: 共有10000条查询结果,搜索用时 15 毫秒
991.
Background
Recently, Marcus et al. (Bioinformatics 30:3476–83, 2014) proposed to use a compressed de Bruijn graph to describe the relationship between the genomes of many individuals/strains of the same or closely related species. They devised an \(O(n\log g)\) time algorithm called splitMEM that constructs this graph directly (i.e., without using the uncompressed de Bruijn graph) based on a suffix tree, where n is the total length of the genomes and g is the length of the longest genome. Baier et al. (Bioinformatics 32:497–504, 2016) improved their result.Results
In this paper, we propose a new space-efficient representation of the compressed de Bruijn graph that adds the possibility to search for a pattern (e.g. an allele—a variant form of a gene) within the pan-genome. The ability to search within the pan-genome graph is of utmost importance and is a design goal of pan-genome data structures.992.
Kaoru Seike Hisashi Hanazawa Toshiyuki Ohtani Shizuo Takamiya Ryoichi Sakuta Michiko Nakazato 《BioPsychoSocial medicine》2016,10(1):15
Background
Many studies have focused on the decreasing age of onset of eating disorders (EDs). Because school-age children with EDs are likely to suffer worse physical effects than adults, early detection and appropriate support are important. The cooperation of Yogo teachers is essential in helping these students to find appropriate care. To assist Yogo teachers, it is helpful to clarify the encounter rates (the proportion of Yogo teachers who have encountered ED students) and kinds of requested support (which Yogo teachers felt necessary to support ED students). There are no studies that have surveyed the prevalence rates of ED children by ED type as defined by the Diagnostic and Statistical Manual of Mental Disorders, 5th edition (DSM-5), nor were we able to find any quantitative study surveying the kinds of support Yogo teachers feel helpful to support ED students.Methods
A questionnaire survey was administered to 655 Yogo teachers working at elementary/junior high/senior high/special needs schools in Chiba Prefecture. The questionnaire asked if the respondents had encountered students with each of the ED types described in DSM-5 (anorexia nervosa (AN), bulimia nervosa (BN), binge eating disorder (BED), avoidant/restrictive food intake disorder (ARFID), and other types of EDs (Others)), and the kinds of support they felt necessary to support these students. The encounter rates and the kinds of requested were obtained and compared, taking their confidence intervals into consideration.Results
The encounter rates for AN, BN, BED, ARFID, and Others were 48.4, 14.0, 8.4, 10.7, and 4.6 %, respectively. When classified by school type, AN, BN, BED, and ARFID had their highest encounter rates in senior high schools. Special needs schools had the highest rate for Others. The support most required for all ED types was “a list of medical/consultation institutions.”Conclusions
Our results have clarified how to support Yogo teachers in the early detection and support of ED students. We found that the encounter rate of AN was the highest, and that it is effective to offer “a list of medical/consultation institutions” to junior and senior high schools where the encounter rates for AN are high.993.
Hideaki Hasuo Kenji Kanbara Hiroko Sakuma Rie Matsumori Mikihiko Fukunaga 《BioPsychoSocial medicine》2016,10(1):27
Background
Carotid sinus syndrome (CSS) can cause prodromal symptoms of syncope such as dizziness and nausea. Patients with end-stage cancer lose self-efficacy associated with reduced activities of daily life (ADL). Herein, we report a case of end-stage cancer in which self-efficacy was enhanced as the patient gained self-control of prodromal symptoms of syncope.Case presentation
A 70-year-old patient with end-stage esophageal cancer and enlarged supraclavicular lymph nodes developed CSS. The CSS was a mixed type with both bradycardia and decreased blood pressure, accompanied by prodromal symptoms prior to syncope episodes. The patient incidentally discovered that he could decrease the duration of symptoms by contracting the muscles in his hands and legs. By applying this coping method at the onset of prodromal symptoms, he was also able to reduce the severity and duration of symptoms, which resulted in enhanced self-efficacy. As a result, the frequency of prodromal symptoms also decreased even though ADL improved.Conclusion
This patient was diagnosed with vasoinhibitory-predominant mixed-type CSS. The coping method the patient developed seemed to avoid the onset of abrupt blood pressure decrease via peripheral vascular constriction action. Achievement of adequate coping such as self-control of prodromal symptoms enabled our patient to improve his self-efficacy even at the end stages of cancer. This case of enhanced self-efficacy could possibly illustrate a placebo effect for prevention of recurrence.994.
Asghar Mohammadi Hesari Hamid Reza Shamlouei Ali Raoof Toosi 《Journal of molecular modeling》2016,22(8):189
The effect of alkali metal oxides M n O (M?=?Li, Na, K; n?=?2, 3, 4) on the geometric, electronic, and linear and nonlinear optical properties of the Mg12O12 nanocage was investigated by density-functional-based methods. According to the computational results, these alkali metal oxides are adsorbed on the Mg12O12 nanocage because this adsorption reduces its energy gap. The static first hyperpolarizability (β 0) of the nanocage is dramatically increased in the presence of the alkali metal oxides, with the greatest increase seen in the presence of the superalkalis (i.e., M3O; M?=?Li, Na, and K). The highest first hyperpolarizability (β 0?≈?600,000 a.u.) was calculated for K3O@Mg12O12, which was considerably more than that for Mg12O12. The thermodynamic properties and relative stabilities of these inorganic compounds are discussed. 相似文献
995.
Bing Zhang Jia Xu Shu-Fan Mo Jian-Xi Yao Song-Yuan Dai 《Journal of molecular modeling》2016,22(12):300
Electron transfer between cytochrome c (Cytc) and electrodes can be influenced greatly by the orientation of protein on the surface of the electrodes. In the present study, different initial orientations of Cytc on the surface of five types of single-walled carbon nanotubes (SWNTs), with different diameters and chirality, were constructed. Properties of the orientations of proteins on the surface of these tubes were first investigated through molecular dynamics simulations. It was shown that variations in SWNT diameter do not significantly affect the orientation; however, the chirality of the SWNTs is crucial to the orientation of the heme embedded in Cytc, and the orientation of the protein can consequently be influenced by the heme orientation. A new electron pathway between Cytc and SWNT, which hopefully benefits electron transfer efficiency, has also been proposed. This study promises to provide theoretical guidance for the rational design of bio-sensors or bio-fuel cells by using Cytc-decorated carbon nanotube electrodes. 相似文献
996.
997.
998.
Xueli Cheng 《Journal of molecular modeling》2016,22(11):282
The absorption and emission spectra of dichlorvos and the dichlorvos-MAA complex in methanol, water, and chloroform in the molecularly imprinted recognition were investigated systematically. The M06-2X results revealed that: 1) the hydroxyl groups in polar solvents such as methanol and water may markedly influence the weak interactions, and then alter the adsorption and emission spectra; 2) the electronic excitation in absorption spectra of dichlorvos is dominated by the configuration HOMO?→?LUMO, but in the most stable dichlorvos-MAA it becomes the ππ* excitation of HOMO?→?LUMO?+?1; 3) Mulliken charges reveal that dichlorvos almost dissociates to Cl- and a cation in its S1 excitation state; 4) the phosphorescence spectra of dichlorvos-MAA are relatively weak. 相似文献
999.
Chaofu Wu 《Journal of molecular modeling》2016,22(4):99
Single- and double-chain models of three stereoregular polymers, iso- and syndiotactic poly(methyl methacrylate) and isotactic poly(vinyl chloride), were extensively simulated using systematic coarse-grained (CG) potentials. It was found that, in vacuum, all of these long chains collapse in a two-stage process from their fully extended configurations into coils, and the two chains in each double-chain model ultimately become intertwined. Strong intermolecular interactions were found to occur between two chains of the same polymer (“like pairs”), which helps to explain the high densities of single-component melts. However, the intermolecular interactions between two chains of different polymers (“unlike pairs”) were stronger than those in like pairs. The enthalpy of mixing for unlike pairs—obtained from their intermolecular interaction energies—was negative, indicating that the two binary blends considered here are homogeneous systems. Moreover, a more negative enthalpy of mixing is suggested to correlate with better miscibility. These results agree well with corresponding experimental and simulated results, once again validating the accuracy of CG potentials when they are used to explore structural and energetic properties. The local structure captured by the isolated long chains dictates the ability to elucidate melt-phase behavior. A scheme involving the preparation of bulk models with initially collapsed chains was proposed; such CG models could be widely used to rapidly screen pairs of polymers for specific applications. 相似文献
1000.