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81.
Eunju?Cheong Margaret?R.?PoolerEmail author 《In vitro cellular & developmental biology. Plant》2003,39(5):455-458
Summary Factors affecting in vitro shoot production and regeneration of Cercis yunnanensis Hu et Cheng were investigated by comparing various growth regulators and explant types. For optimum shoot production from
axillary buds, Murashige and Skoog (MS) media containing 6-benzyladenine, either alone or in combination with a low concentration
of thidiazuron, resulted in the greatest number of shoots formed per explant (>3). Explants (2 mm long) containing one axillary
bud placed in directcontact with the medium yielded the most shoots per bud (1.6) when grown on growth regulator-free medium.
Root formation on 70–80% of shoot explants was accomplished using either indole-3-butyric acid or α-naphthaleneacetic acid
in the medium, with significantly more roots formed on explants possessing and apical bud than those without the bud. Direct
shoot organogenesis from leaf explants occurred on MS medium containing 10–30 μM thidiazuron, with up to 42% of leaf explants producing shoots. 相似文献
82.
An efficient system for clonal mass propagation in liquid culture was established for the propagation of ornamental gentian.
In a test of the requirements for three cytokinins [6-benzylaminopurine, N-(2-chloro-4-pyridyl)-N′-phenylurea and N-phenyl-N′-1,2,3-thiadiazol-5-yl urea (TDZ)] in combination with 1-naphthaleneacetic acid (NAA), we found that effective propagation
of shoots occurred with 0.01 mg l–1 TDZ in a 300 ml conical flask that contained 100 ml of medium. The propagation of shoots was also affected by the concentrations
of macronutrients (KNO3, NH4NO3 and CaCl2) and sucrose in Murashige and Skoog's (MS) medium, and it was influenced to some extent by the speed of agitation on an orbital
shaker. The most efficient propagation of shoots was achieved in full-strength MS medium supplemented with 0.01 mg l–1 TDZ and 20 g l–1 sucrose with agitation at 150 rpm. The propagation of shoots was maximal after 6 weeks of culture (140 shoots from five nodal
segments in one flask). Large-scale propagation in a 5-l fermenter was attempted using 3 l of MS medium that contained 0.01
mg l–1 TDZ and 20 g l–1 sucrose. More than 2,000 shoots were obtained in the fermenter in 5 weeks following the initial cultivation of five nodal
segments for 6 weeks in one 300-ml flask. The shoots that had propagated in the fermenter were transferred directly to soil
without prior rooting in vitro and were easily acclimatized within 1 month.
Received: 7 October 1997 / Revision received: 16 January 1998 / Accepted: 30 January 1998 相似文献
83.
On‐line yeast propagation process monitoring and control using an intelligent automatic control system 下载免费PDF全文
The monitoring and control of bioprocesses is a challenging task. This applies particularly if the actions to the process have to be carried out in real‐time. This work presents a system for on‐line monitoring and control of batch yeast propagation under limiting conditions based on a virtual plant operator, which uses the concept of intelligent control algorithms by means of fuzzy logic theory. Process information is provided on‐line using a sensor array comprising the measurement of OD, operating temperature, pressure, density, dissolved oxygen, and pH value. In this context practical problems arising through on‐line sensing and signal processing are addressed. The preprocessed sensor data are fed to a neural network for on‐line biomass estimation. The root mean squared error of prediction is 4 × 106 cells/mL. The proposed system then triggers temperature and aeration by usage of a temperature dependent metabolic growth model and sensor data. The deviation of the predicted biomass from that of the reference trajectory as modeled by the metabolic growth model and its temporal derivative are used as inputs for the fuzzy temperature controller. The inputs used by the fuzzy aeration controller are the deviation of measured extract from that of the reference trajectory, the predicted cell count, and the dissolved oxygen concentration. The fuzzy‐based expert system allows to provide the desired yeast cell concentration of 100–120 × 106 cells/mL at a minimum residual extract limit of 6.0 g/100 g at the required point of time. Thus, a dynamic adjustment of the propagation process to the overall production schedule is possible in order to produce the required amount of biomass at the right time. 相似文献
84.
Mi-Kyung Lee Nak-Jung Kwon Jae Min Choi Im-Soon Lee Seunho Jung Jae-Hyuk Yu 《Genetics》2014,197(1):159-173
Asexual development (conidiation) of the filamentous fungus Aspergillus nidulans occurs via balanced activities of multiple positive and negative regulators. For instance, FluG (+) and SfgA (−) govern upstream regulation of the developmental switch, and BrlA (+) and VosA (−) control the progression and completion of conidiation. To identify negative regulators of conidiation downstream of FluG-SfgA, we carried out multicopy genetic screens using sfgA deletion strains. After visually screening >100,000 colonies, we isolated 61 transformants exhibiting reduced conidiation. Responsible genes were identified as AN3152 (nsdD), AN7507, AN2009, AN1652, AN5833, and AN9141. Importantly, nsdD, a key activator of sexual reproduction, was present in 10 independent transformants. Furthermore, deletion, overexpression, and double-mutant analyses of individual genes have led to the conclusion that, of the six genes, only nsdD functions in the FluG-activated conidiation pathway. The deletion of nsdD bypassed the need for fluG and flbA∼flbE, but not brlA or abaA, in conidiation, and partially restored production of the mycotoxin sterigmatocystin (ST) in the ΔfluG, ΔflbA, and ΔflbB mutants, suggesting that NsdD is positioned between FLBs and BrlA in A. nidulans. Nullifying nsdD caused formation of conidiophores in liquid submerged cultures, where wild-type strains do not develop. Moreover, the removal of both nsdD and vosA resulted in even more abundant development of conidiophores in liquid submerged cultures and high-level accumulation of brlA messenger (m)RNA even at 16 hr of vegetative growth. Collectively, NsdD is a key negative regulator of conidiation and likely exerts its repressive role via downregulating brlA. 相似文献
85.
86.
87.
William D. Thomas 《Analytical biochemistry》2010,407(2):237-240
Phage display is used to discover peptides or proteins with a desired target property—most often, affinity for a target selector molecule. Libraries of phage clones displaying diverse surface peptides are subject to a selection process designed to enrich for the target behavior and subsequently propagated to restore phage numbers. A recurrent problem is enrichment of clones, called target-unrelated phages or peptides (TUPs), that lack the target behavior. Many TUPs are propagation related; they have mutations conferring a growth advantage and are enriched during the propagations accompanying selection. Unlike other filamentous phage libraries, fd-tet-based libraries are relatively resistant to propagation-related TUP corruption. Their minus-strand origin is disrupted by a large cassette that simultaneously confers resistance to tetracycline and imposes a rate-limiting growth defect that cannot be bypassed with simple mutations. Nonetheless, a new type of propagation-related TUP emerged in the output of in vivo selections from an fd-tet library. The founding clone had a complex rearrangement that restored the minus-strand origin while retaining tetracycline resistance. The rearrangement involved two recombination events, one with a contaminant having a wild-type minus-strand origin. The founder’s infectivity advantage spread by simple recombination to clones displaying different peptides. We propose measures for minimizing TUP corruption. 相似文献
88.
Robin G. Crump Michael F. Barker 《Journal of experimental marine biology and ecology》1985,88(2):109-127
Sexual reproduction and asexual reproduction by fission were studied in four populations of Coscinasterias calamaria (Gray), two in Otago Harbour in the South Island of New Zealand and two in the North Island near Auckland. The annual reproductive cycle in both islands of New Zealand is clearly defined with a spawning season between November and January. In both sites the pyloric caeca index was approximately inverse to the gonad index cycle as found in other forcipulate asteroids. There are substantial differences in the sex ratios of mature starfish at each site studied, with 1:1 ratios in two populations, one population heavily biased towards females and the fourth consisting almost entirely of males. Morphometric variation in arm number due to splitting was studied and the frequency of splitting varied considerably between the four populations. Generally speaking sublittoral C. calamaria divide less frequently than intertidal starfish and populations in which food is less abundant or of poorer quality are more fissiparous and put less energy into sexual reproduction, than populations with plentiful readily available food in the form of mussels. The significance of the different reproductive patterns in C. calamaria is discussed. 相似文献
89.
Ultrasound and matter--physical interactions 总被引:3,自引:0,他引:3
Humphrey VF 《Progress in biophysics and molecular biology》2007,93(1-3):195-211
The basic physical characteristics of ultrasound waves are reviewed in terms of the typical displacements, velocities, accelerations and pressures generated in various fluid media as a function of frequency. The effects on wave propagation of interfaces are considered, and the way in which waves are reflected, transmitted and mode converted at interfaces introduced. Then the nonlinear propagation of high amplitude ultrasound is explained, and its consequences, including the generation of harmonic frequencies and enhanced attenuation, considered. The absorption of ultrasonic waves and the resulting heat deposition in absorbing media are described together with factors determining the resulting temperature rises obtained. In the case of tissue these include conduction and perfusion. The characteristics of cavitation in fluid media are also briefly covered. Finally, secondary nonlinear physical effects are described. These include radiation forces on interfaces and streaming in fluids. 相似文献
90.
In distylous, self-incompatible plants, clonal propagation, unbalanced floral morph frequencies, and reduced population size can interfere with the functioning of distyly by compromising legitimate intermorph pollinations, resulting in reduced reproductive output. Here, we examined the mating system and the impact of mate availability, population size, and spatial aggregation of morphs on reproductive output in the distylous, clonal, aquatic plant Hottonia palustris. Controlled pollinations under greenhouse conditions detected no spontaneous selfing without the action of a pollen vector (autonomous autogamy) and demonstrated very low fruit and seed development after self-pollination. Intermorph (legitimate) crossings resulted in high reproductive output in both floral morphs (long- and short-styled individuals), whereas intramorph (illegitimate) crossings decreased fruit and seed development by more than 50%, indicating that the species has partial intramorph-incompatibility. In natural populations, small population size and increasing deviation of floral morph frequencies negatively affected reproductive outcome. Individuals of the majority morph type developed significantly fewer fruit and seeds than individuals of the minority morph type. This rapid decline in fecundity was symmetrical, indicating that regardless of which morph was in the majority, the same patterns of negative frequency-dependent mating occurred. Increasing spatial isolation between compatible morphs significantly reduced fruit and seed set in both morphs similarly. This study provides clear indications of frequency- and context-dependent mating in natural populations of a distylous plant species. 相似文献